Toyota Prius, other hybrid and EV stuff, and related links

Many items in this file are out of date by now.
Link stability is completely subject to each provider's whim, and by now this file hasn't been fully reviewed/checked in several years.

Direct links to Priuschat threads eventually got converted to the new format, and fortunately the majority of thread index numbers there haven't changed or gone missing over the years.

For easy reference, this file is
    Last *real* update: 140827
    For more recent car stuff where we go full-electric, see this

Quick-n-dirty tag index

    Informational / howitworks
    Service and teardowns
    The 3rd-gen Prius
    General articles
    Forums and newsgroups
    Toyota resources
    Dealers / vendors
    Traffic and fuel economy
    Project sites
Printable one-page "tech info" flyer pointing to this site. Geeky. Uses one of Toyota's old graphics overlaid with the fundamental HSD design diagram from one of the original Prius-related patents.

Informational / howitworks and other helpful pointers
An easy way of forcing the engine in a Prius to start and idle, for inspection or diagnosis purposes. Works around the "Georgia problem". This method bears no risk to the transmission, whereas the more complex "inspection mode" may if misused.]
Some really well-designed presentations and discussion about how the Prius works, especially the planetary drivetrain.
Minor rework of Graham's nomograph, extended to higher RPM [particularly on the negative side, reflecting high-speed coasting], and with a schematic of the planetary gearset thrown in.
One perceptive and knowledgeable owner's long-time logs, photo galleries, handouts/flyers/cards, link-nests, and lots of information. Almost every other Prius-related site out there points to him.
Several useful FAQs and checklists hosted by Tom Stangl.
Another tech rundown on the Prius [with help from Graham] from a New Zealand car dealer that specializes in hybrids. and
Mirror of Toyota's Hybrid Synergy Drive description [two parts]. Was originally hosted at and
until some destructive asshole hacked the site and the whole "files" section got zorched. Fortunately, I had a backup copy, so here it is.
The original "EV-button" hack description. [1.4Mb]
Various shots of cutaway Prius transaxles; #4 is the second-gen design.
Wayne Brown, one of the seminal Prius hackers, maintains a good info site that only *hints* at some of the amazing analytical work he's done. He's also one of the foremost "extra batteries" experimental pioneers.
  [a rework of what was
  which seems to have vanished in the meantime]
The five stages of Prius hybrid operation. Describes operational phases that the HSD system passes through while warming up.
In-depth explanation of the "B" shift-selector position and its purpose, uses, and quirks.
Description of high-speed "glide" mode that uses no fuel, and how to find it. Another in a series of "prius subtleties, because people always ask" articles.
The answer to a common complaint about Prius brakes feeling "grabby" or otherwise strange, particularly when nearing a stop at about 7 mph. The fix? Throw it in neutral to disable regen during a couple of stops, and the stuff scrapes right off.
Test-bench exploration of why regenerative braking can work at low motor RPM and still produce sufficient voltage to charge a high-voltage battery. Yay, inductance.
A large and well-maintained collection of Prius articles, reviews, sites, news, etc by Mr. J. Kash, a history teacher. Updated link.
Power output, efficiency, and [theoretical] BSFC curves for the Prius internal combustion engine [ICE], taken from various sources. Illustrates the effects of optimal loading, about where that occurs with the THS, and how the throttle control algorithm makes every effort to optimize it.
    [!oops, broken link!   Here's a backup copy]
shows a more typical BSFC map [from this report, which seems to have gone missing now] and the options for obtaining various fractions of engine output power. This places the sweet-spot around 1800-2000 RPM at high shaft load, which is also about the real-life truth for the Prius engine albeit at somewhat lower torque.

Animated illustration of how the original Atkinson variable-displacement engine work [and many other types -- great site]
Illustration of Toyota's Atkinson/Miller cycle, showing how they also optimize variable intake valve timing as well. Several running modes shown. Range 4 is where you want to be on the highway.
Investigation into Prius variable intake valve timing at highway speeds, smashing various prior theories about operation, and general details on how crank and cam sensors work. A veritable blizzard of scope traces.
A really good paper/presentation on different "hybrid synergy" drivetrains and rationale.
NHTSA/DOT starter interlock and transmission safety standards NPRM for hybrids, that explains the whole rationale about "creep" force and directional cueing for a driver.
Some more general hybrid news and forum sites.
Alt Wheels, for a while the largest yearly Boston-local conference/show on alternative fuels, sustainable transportation and infrastructure, and lots of cool vehicles displayed on the MOT lawn. For '06 and beyond, it has moved to Boston City Hall Plaza. Some of us did a fun group booth in '07.
The "Naked Prius" tech exhibit takes top honors at AltWheels 2005! Shows the leadup and easily-removed parts, too.
Prius discussions at Toyoland, a Toyota enthusiast site [run by Allpar]
In the "john with numbers" group of contributors, another good general site about all generations of the Prius. Has a good chunk of early info about the 2010 model. Mostly in Dutch, though.
Tons of good auto-tech info with heavy Toyota emphasis. In fact, all of is very useful -- recommended reading for pros and weekend warriors alike. A notable item is "Understanding Toyota Wiring Diagrams". Much of this is original Toyota hybrid tech training material, evidently now released to the general public without subscription cost.
The Panasonic-EV website, recently renamed to "Primearth" [which conveniently didn't change their domain name!] detailing ongoing improvements in their NiMH battery modules. They manufacture the Prius HV pack modules, as well as batteries for several other vehicles including minivan form-factor ones that after five years, are inexplicably STILL not sold into the US market.
Details on the [2rd-gen] Prius 12 volt battery -- dimensions, type, the mounting area, voltage regulation, and quiescent drain. Please contribute to the knowledge here -- there has *got* to be a good aftermarket unit that will fit in this space and not cost $160 from the Toyota dealer! UPDATE -- there is one, see the second part of the page for the answer.
Video from when I visited Bernie on a roadtrip, with three years of faultless service by then on the Yellowtop I had ordered from him in 2008. As of early 2014, it's still going strong after six years!
  was: until Jan 2008]
A thread revealing the existence of a means to completely reset the Prius' list of valid keys and program new ones, WITHOUT having to swap out any ECUs. Works through the THHT, aka Vetronix "Mastertech MTS3100" scantool.
A FAQ that some people tried to put together on a wiki, but not only gets a lot of stuff wrong, it's got the typical wiki problem -- no control over misinformation and flat-out vandalism. Take with a large grain of salt. Open wikis don't entirely suck, *people* suck.

Service and teardowns

Taking things apart, reverse-engineering, diagnosis, and repair hints.
      [backup copy here]
U.S. government-funded studies of the Prius at Argonne and Oak Ridge. Useful data, and really drives home how Toyota is completely kicking our asses from an engineering standpoint because we couldn't figure out how to build it ourselves.
The 890029.PDF link is a more final report, and includes several good pictures from inside the Prius inverter and driveline. If it turns up moved or missing from the OSTI site, use the local copy here.
A deep investigation into the Prius inverter, covering how it's assembled and beginning extensive analysis of the electronics. Ongoing project.
Some shots of a disassembled 1.5L engine block during a resealing job.
Technical training information, primarily on the Prius but also covering basic 3-phase motors and inverters, with pointers to other hybrid training info freely available on the net. The Prius material alone can easily fill a full-day seminar, or more if coupled with hands-on demos and work in a shop. If you're not up to speed on hybrid service yet, here's where to look!
What service items does your Prius really need, and when? The dynamic duo of Galaxee and her Dear Husband set it all out for you here. Beware of the "upsell" when you don't need it!
Changing the PSD transaxle fluid in an '04, using the seekrit undocumented top fill plug. Shows shifting the inverter around without draining its coolant, to access items under it. Some other minor but useful maintenance items are discussed here too.
More maintenance items to take care of as the '04 hits the 100,000 mark and beyond, including extensive discussion of coolants and brake fluids and their expected lifetime vs. their real-life condition at this point. The inverter cooling pump is also changed, as it's commonly found to start wearing out around the same time. An engine-temp fakeout is finally installed and the MAF and various other parts are inspected and commented on.
Discussion/pictorial of Prius brake cleaning and service, not that it's nearly as necessary as in non-hybrid cars! But yearly cleanout and particular attention to keeping the front caliper slide-pins free to move is a good idea nonetheless. Includes details on how the rear drums self-adjust the shoes.,%20v1.03.pdf   [long URL!]
    -- seems to have fallen victim to domain squatting, so here's a backup copy:
An excellent guide to carefully removing the dashboard panels and MFD to get to and behind the stereo. If you're going to do work around the dash in general, read through this first. And boycott Dotster when shopping for domain registrars.
Finding and fixing a common fault in the display screens of some '04 and '05 Priuses. Requires fairly small-scale work, but should be within the capability of most electronics hobbyists.
Details on removing and disassembling the "body ECU" and main connector block from under the dashboard.
How to fix a factory-assembly problem that can cause damage to the motor control harness, due to a starter blockoff-plate fitted backwards that places a sharp metal edge right next to some very important wiring.
Tail light assembly removal, with pictures. Some of the inner trim needs to come out first, then it's two bolts.
Exploration inside the Prius battery box, at six years and 130K miles, to check for any potential [!] problems and play with high voltage and hybrid system isolation. Includes a good look at the cooling fan hardware, and a brief dip into what's inside the brake reserve power-supply box as long as we're fooling around in the back of the car.
An expose' of the gas tank bladder, done by Galaxee's hubby after he replaced a tank that had been hopelessly overfilled to the point of ruining the EVAP stuff.
Backup hosted copy of Doug Schaefer's document on renovating the NHW11 (Classic) accelerator pedal after it starts exhibiting the sluggishness "big hand" syndrome. The NHW20 uses non-contact Hall-effect sensors and is thus immune to this problem.
A look inside the electric coolant pump that runs the separate radiator loop for the Prius inverter and motors, and a best-guess theory on why these things fail somewhere around 100K miles.
Dead link.  Alldata USED to have a nice non-subscription mirror of Toyota TSBs, especially ones that describe known problems/issues/fixes with certain model-year cars. They've apparently gone mercenary and taken it down in favor of the new "alldatadiy" structure. Do WHAT yourself, huh? Nice way to help the community.
Florian Steiper's failed 2002 transaxle, which he disassembled to reveal some burnt motor windings. There have been a few instances of this in 2001 and 2002 "Classic" Priuses, and the jury is still out on whether this is from an inherent design flaw, overlooked maintenance, or just some unlucky owners.
Where to find some manuals, parts, and lists of dealers. Script-based, may not work in all browser environments.
Removal and cleanout of the Prius driver's door lock cylinder, which is much easier than expected and does NOT involve extensive door panel disassembly.
Gordon Jennings writes on proper spark plug selection, and how to read an engine's running conditions from the condition of the plugs.
A pictorial essay on the Prius electric throttle body, how to test it, and
how to do routine service on the mechanism without complete removal from the car.
How to adjust valve clearance on the 1NZ-FXE engine, by measuring and replacing the little cam-follower buckets. Should rarely be necessary, however -- Prius engines generally have a history of going multiple hundred thousand miles with virtually no mechanical service.
The innards of the dash-lights "rheostat" in the Prius. It's actually a low-side PWM unit with a couple of other control leads that tells the MFD to go full-bright or dim. A proper LED brightness booster for the frequently complained-about steering wheel button backlight would have to deal with this as either a control input or its negative supply rail.   [long URL!]
Links to some ASA articles on servicing hybrids; good info for both independent auto techs and shadetree wrenchers. Slightly out of date, since it seems to mostly deal with the Classic prius.
International Automotive Technician's Network, a large forum where auto techs hang out and swap advice, ideas, rants, etc. Subscription needed for most of the areas but there is some free info available and the freely viewable day-to-day question/answer summaries can be interesting.
The innards of the Coastal ETech cruise-control based EV-mode switching circuit. Uses a micropower comparator and accumulates enough charge from the inputs to fire a transistor and ground the pin. Easily enough visual info to reverse-engineer your own clone, although I personally like the immediacy and simplicity of a straightforward pushbutton.

Also see the nest and Prius-camping page below for details on the A/C blower controller.
Archived newsletters from the Massachuestts vehicle inspection and testing administration, geared toward inspection personnel. Often covers several interesting OBD-II and emissions-monitoring diagnostic topics.

The third generation

Articles and information relating to the 2010 and later model Prius, which had quite a bit of buzz surrounding its introduction in early 2009.
Photo gallery of test-driving the 2010 in Orlando.
The main Priuschat thread on the 2010 and beyond (third-generation) models. There are several other 2010+ related areas including maintenance and technical discussion on Priuschat, which also served as a semi-official info-clearinghouse during the launch. Around that time Toyota's marketing arm finally started actually *participating* in some of the forums, after years of silent snooping.   [long and now broken URL!]
The official 2010 Prius introduction pictures, from Toyota and hosted by Danny at Priuschat.
The "hybrid system indicator" display screen introduced in the 2010 Prius is analyzed and compared to the earlier model cars, and some best-efficiency usage hints are explained. Warp stealth is now easy to find and maintain without extra instrumentation!
A Priuschat thread on reverse-engineering various CAN / OBD-II information in the third-gen Prius. The real meat begins when "frenchie" chimes in around message 27, and gets quite interesting in subsequent pages. It only took six months or so for the community to sniff enough network traffic to generate a useful set of Xgauge progamming for the 2010 model, but it is naturally an ongoing process.
Research toward the most streamlined way to install an engine block heater in the 2010+ Prius, which is a little more complex than the second-gen.

General Prius / hybrid articles

Events, stories, news clips, videos, and random items of interest.
It is not our fault that some sites where these are/were hosted chose to arbitrarily move stuff around or delete it later on.
Article on the Canadian cab driver who went over 200,000 miles in his first Prius and continues to rack up more miles than just about anyone else.
110 MPG and a 1400-mile tank in a stock Prius: A small bunch of dedicated crazy geeks spent a weekend in Pittsburgh to shatter previous mileage records. These forum threads detail the whole "Marathon" story and point to related items. Extreme pulse-n-glide.
Various press about hypermiling and/or Hybridfest, summer 2007.
Observations on a Prius "sweet spot" engine efficiency range, yielding improved MPG at mid and higher speed ranges with proper application. Contains an update with some refinements, instrumentation notes, and a long-term perspective on it all.
Prius land speed record tests at Bonneville, by a team from Toyota and Car & Driver.
Car & Driver review of the 2004 Prius.
Birth of the Prius, an article on development history and market acceptance
Fun article on hybrid service and features by the folks at Art's Automotive, a service shop in Berkeley CA that loves hybrids.
The "creative lab scope technique" page, endorsing out-of-the-box thinking when diagnosing automotive problems with scopes and similar equipment. Sign-up required for the actual articles. There is also a forum area.
Article about synthetic oil and engine life.
[was:$27281 which appears to be gone]
Good reasons to run higher tire pressure in police vehicles, as well as any others.   Sidewall or better is perfectly safe for a modern car tire.
[this used to be something ending in "...article.jsp?siteSection=19&id=27281" which went dead, but there's an obvious pattern which should work if you're looking for any other articles. If the above link goes invalid, here is a backup copy without the original layout/formatting.]
A serious WARNING about inferior aftermarket valve stems that could crack and leak in a relatively short time. Affects all cars, especially newer ones that are supplied with higher-pressure tires.
Good info about many battery technologies, types, charging, safety, etc.
A pictorial essay about how well a Prius handles large loads, especially with mods to distribute the weight better.
Interview with Ron deLong, inventor of the Scangauge.
A rant engendered by a rather horrendous "web experience" at Toyota's service-manuals subscription site.   [Video]
Carolyn Coquilette [Lusciousgarage] on Prius accelerator pedals, floor mats, and the elusive "unintended acceleration" problem.
Good explanation of ABS, traction control, and vehicle stability control.
Part technical rundown, part opinion piece on the whole "sudden unintended acceleration" and 2010 Prius braking issues dust-up. Tries to cut through some of the political theatre going on with this.
==>   And guess what? A year later, the NHTSA concludes that the vast majority of such incidents are driver pedal misapplication. Case closed.
The hatch area of a third-gen Prius turns easily into a cozy and relatively private sleeper-berth, and there's even a way to run the ventilation system on very low power without needing the rest of the car turned on.
Hobbit's running Prius diary/blog/whatever. Points to a number of the mods and hacks listed here, and places them in a back-story and timeline. In perpetual flux, and often out of date with the present. If nothing else, it describes the purchase rationale and process when this whole thing started.

PHPbb-based discussion forum; quite active. Has technical areas and downloadable FAQs and a strong overall sense of community. Using the forum search engine can be quite productive, and can be done by anyone without having to sign up first.

[IMPORTANT NOTE regarding Priuschat:

   Since its changeover from IPB to vBulletin in Dec 2007 and then to whatever
   else later on, along with the associated database migrations, some of the
   old thread numbers have changed and thus caused externally and internally
   linked threads and articles to be broken.  They are still in there somewhere
   and you can still do searches; they might just turn up as different topic
   numbers anywhere from about 700 to 1400 numerically lower than the
   corresponding old ones.  No idea if/when this will ever get fixed.]
Similar to priuschat, but a more obfuscated presentation. Also has a good knowledge-base section.

Where a lot of the "hypermilers" hang out. Get your high-mileage technique pointers here -- for any vehicle, not just hybrids! No gimmicks, no cow-magnets or hydrogen bubblers or gas pills, just solid and proven results simply from improved and significantly safer driving skills.

Yahoo groups

WARNING: Yahoo-group sites generally want cookies enabled.
Most of these groups have publicly-accessible archives, such that you can read all the postings without needing a Yahoo account or signing up for the group. Some of the groups have a /files/ section for uploaded FAQs and pictures and such, but apparently those are accessible only to Yahoo accounts that are actually also members of the group, and nobody's figured out how to make the /files/ sections publicly readable. Some of the information is duplicated elsewhere that is more accessible.


An attempt to route around the pervasive Flash and scripting damage that Toyota insists on shoving down web visitors' throats, and actually point to the real information. This could change next week; no guarantees.
Technical Information System [TIS], where online service manuals reside [on a paid subscription basis]. An absolutely horrendous site design that relies way too heavily on scripting bells-n-whistles, and assumes that everyone happily runs IE with no security turned on.
Techstream, the next generation of Toyota's dealer scantool that integrates OBDII and OEM diagnostics with internet links to Techinfo via wireless infrastructure in and around the service bay. Ruggedized laptop-based. Rumored to be based on an OTC/SPX scantool product rebranded for Toyota. Vetronix has lost their long-time hold on this market.

techinfo-erg.html   (local copy)
Emergency response guides for various Toyota hybrid and alt-fuel vehicles, aimed at teaching first-responders about hybrid vehicle rescue safety and how to not cut the orange wires. These guides are nice technical rundowns on the vehicles themselves, and well worth reading. Bottom line is that fuel tanks and airbag squibs are far more hazardous than HV batteries and wiring.
Discussion of THS-II design. [This actually begins a whole sequence]
Discussion of THS-II controls.
Toyota R&D Labs. [english]

Dealers / vendors
Info on the Tamagawa-Seiki position resolvers used in the Prius BLDC motors, which bring sine and cosine information back into the hybrid ECU. Includes a little bit about the AU6802N1 "smartcoder" support chip, two of which sit on the hybrid controller. This product family is aimed at the hybrid automotive market, and it's quite amusing to see a picture of an Estima right there on top of their car applications overview page!
Mini-scanner site, for the Classic Prius only. Also by graham1.
The CAN-View site, detailing a very cool CANbus monitoring product that displays on the built-in screen *and* accepts touchscreen control commands. For '04+ Prius, with and without Nav. A really nice bit of integration engineering, not to mention the ability to pull out and display all that "geek info".
A salvage dealer and car-repair outfit specializing in rebuilding crashed Priuses and/or parting them out. Great source of discounted parts, both working and nonworking, depending on availability. This guy has done some completely amazing recovery of hopeless-looking wrecks, and has gotten into fixing inverters down to the component level, reverse-engineering ECUs, installing PHEV conversions, you name it.
One of the early Prius pioneers, Dan Kroushl, headed for Autobeyours for his 180,000 mile maintenance and some other fun fixups, and wrote it up with lots of pictures.
Metro Toyota has several add-ons for the Prius, including engine block heaters [but you have to ask Jesse specifically for those]. Bulk buys of block heaters often happen via Priuschat -- search the forums.

Carolyn Coquilette's shop, specializing in hybrid diagnostics, repair, maintenance, and modifications [including PHEV]. A very interesting and environmentally-conscious approach to automotive servicing, and a fun blog (if you can get the site to work). [US] [Europe]
Small format OBDII [now incl. CAN] scan-tool and digital gauge kit designed to install right on a dashboard. Generic parameters only, although a feature called XGAUGE to display manufacturer-specific enhanced info is under development. The newer Scangauge II can also read DTCs and reset the MIL.
Sites for a few of many commercial laptop-based OBDII scantools. Some of these are designed for the professional and claim to include all the factory-OEM features and parameter-awareness as the "official" tools. This is still not entirely true, but they're making progress.
Another OBDII tool, but with very poor support. Sorry, Alex.
Big Brother data recorders for your OBDII.

Automotive Tech Training, offering in-depth, hands-on hybrid training classes for independent auto techs to come up to speed on hybrid principles, repair, diagnosis, safety, etc. Helping to dispel the myth that all hybrids must go back to the dealers for service, and leading the way to a time when full or at least mostly electric propulsion will be the everyday norm in the bays. $$. Good link-nest to tool companies and other useful auto-tech info.
Craig van Batenburg's instruction center for repair techs. $$$.

Traffic and fuel economy

    [Don't let this happen to you!]
The seminal articles on "traffic waves" and how leaving generous following distance HELPS EVERYONE on the road. The Prius, and the "damped" styles its drivers tend to learn and adopt for better mileage, are very compatible with the jam-busting techniques described here.
More articles relating to "pulse-n-glide" and other high-mileage hints. See the last of these, prius-rally-hints, if you're planning on entering any sort of mileage competitions in a Prius.
Pointers for getting better mileage from *any* vehicle, not just hybrids.
Basic hints on driving efficiently; a set of articles often referenced by other media.
Edmunds tests and reports on various fuel-saving techniques. From 2005, but the most poignant conclusion -- "stop driving like a maniac" -- is equally valid today.
Autospeed article on Brake Specific Fuel Consumption, one of the major factors affecting efficient combustion-engine operation.
Power generally required to overcome air resistance at different vehicle speeds.
European campaign to promote "ecodriving", or better techniques for improving MPG and safety with driving style. Training efforts are already underway in the Netherlands and spreading across several other countries.
Visual guide to evaluating distance and time in tailgating offenses, useful for reporting unsafe conditions based on quick pictures snapped on the road. Fight back against highway terrorism, even if it means that some people need to explore different careers!
Great rant on why "nanny cars" with overly-mollycoddling safety and convenience features are killing us by creating more bad drivers.
Sensible rules for road safety. If demonstrated knowledge of these things were *required* to obtain and hold a driver's license, we would all be so much farther ahead -- but likely with far fewer people licensed to be on the road.
A proposed "state of the union address" segment introducing the idea of a country-wide campaign to universally endorse and enforce safe vehicle following distances of three seconds or more. Unlikely to ever go out over national TV, but it's nice to dream sometimes.
Promo site for the "Traffic Safety" book by Leonard Evans. He has many interesting ideas, such as distributing traffic penalty monies back to all drivers, and other proposals to encourage safer *behavior* on a wide scale.
The "Yuppie Button", a defensive way to use rear-firing lights to help maintain safe space on both ends of the car. Some hardware/wiring modification required. Turns out that it's a prototype of enhanced stop-lighting ideas now under consideration at the NHTSA.
More evidence on the dangers of cellphones and other distractions while driving. Put that thing down and PAY ATTENTION!
ABC News interviews Wayne Mitchell about hypermiling techniques. Wayne is the "block heater guy", who has traveled all over the country installing engine-block heaters for many other owners just because it's a good thing to use for increasing overall MPG -- even in warm weather. It still puts energy into the system, from the wall rather than from burning fuel.
Buick vs. Kenworth == six feet under: what happens when a car driver fails to notice an oncoming semi-truck and pulls out in front of it. Shot by "300kmileprius" at CleanMPG, who sent it along to be hosted here and relates: "Location was Salem, Indiana; late June 2006. Nearly forty people had gathered around by the time I happened to arrive. I just walked up to the front of the crowd, snapped a couple of pictures, and walked away."
Analysis of driving psychology and road-rage. This site is full of excellent related articles. What are YOU thinking behind the wheel?
Getting a little extreme with the safety/conspicuity enhancements on a Prius, as part of ongoing efforts to maintain safe spacing and visibility in traffic especially at night. Simple but effective use of industrial marking products.
EcoDriving USA, an arm of the Auto Alliance in Washington DC, offering various educational material and advocacy on ecodriving. Warning: mostly javascript and Flash based, even if all you're looking for is simple information. They have a fairly complete PDF manual on the subject available for download, albeit the advice within is pretty much the same generic stuff found everywhere else -- directly linked here because finding it over there is challenging at best.
One viewpoint on what hypermiling/ecodriving is all about, sort of in response to the bad publicity gaffe that the AAA public-relations people came up with about the "dangerous hypermilers" on the road. Far from it! (PDF)
Resources advocating increased installation and use of roundabouts / rotaries, proper design and usage of which have proven congestion-reducing effects. Roundabouts are also great for the hypermiler, allowing much more accurate planning as opposed to trying to second-guess a signal.
The other articles/papers at are also quite interesting and relevant.
Federal Highway Administration info on roundabouts/rotaries. A largish PDF, but well worth reading.
Mike Spack, a traffic engineer, discusses roundabouts and lots of other stuff.,4273,4451623,00.html
Miscellaneous articles on roundabouts, "naked intersections", and surprising insights about the rules of urban travel.
Tom Vanderbilt, author of "Traffic" and the howwedrive site, discourses on the benefits of roundabouts.
The "diverging diamond" interchange, which allows greater routing efficiency and easier "left turns" in a smaller paved footprint. Takes a little getting used to by drivers, who wind up proceeding on the left side of the road for a little bit.
Thoughts on why our underlying animal instincts may have trouble seeing electric vehicles as sufficiently "sexy".
Review/comparison of two GPS units from the same company, clearly revealing the decline and fall of Garmin. In terms of UI design and not insulting a buyer's intelligence, they're done.

Project sites and other fun pages
One of the first groups working on plug-rechargeable battery mods to the Prius, which they're calling Prius+. Very vocal and high-profile about their work, and recently announced the EnergyCS pluggable-Prius modification, expected to go fully commercial soon. See also,,, and the "priusplus" yahoogroup.
Mike Dabrowski's extensive resource about the Honda Insight, his MIMA modifications, electric cars, tech training, and many other hybrid and alt-fuel projects and inventions. He is the true guru of the Honda Insight, which is still the fuel-economy leader after all this time.

[*Note: there are many references to "" from here down -- a justifiable bias, since they document all *my* hacks.]
An amusingly simple wiring hack to enable the power windows in a Prius without turning on the rest of the car. Also contains some details on safely removing the dashboard vents and panels without breaking them.
Details on building an analog battery current meter to read flow into and out of the hybrid pack. Uses the stock Toyota hall-effect sensor.
Details of L. David Roper's Hymotion conversion process and observations.
A very simple "engine is running and consuming fuel" indicator, described by a very silly webpage. This has since been merged into an instrument panel.
To squirt or not to squirt, that is the question. Here's the answer to the latter; a very simple fuel-cut switch that also allows playing around with various engine-failure conditions. Also has some discussion of the "high-speed EV" modes being offered by various PHEV providers, and why they might not be such a hot idea after all.
How to install an aftermarket tachometer into a Prius, including notes on how tachometers work, how to test and calibrate them, and how to hack an older one to be compatible with the car's signal levels if necessary.
A modification to the regenerative braking system on the Classic Prius, to make greater use of regeneration and less of the brakes.
Working prototype for a hydraulic-brake-pressure monitor, that helps determine when you're no longer regenerating.
An experimental hack to redirect engine air intake from a warm air source rather than a cold one, with the intent of increased winter economy. Some controlled-test results are posted underneath. See also: "heatgames" ...
Winter preparation: an improved version of the above warm-air intake, plus a detailed account of removing the cowl above the engine and installing a block-heater from above. If you're thinking that the big piece that the wipers fit onto is scary, it isn't! These pages make cowl removal easy.
A circuit to read the raw output voltage from the engine coolant temperature thermistor, and convert it through a "linearizer" to a reasonably close mapping from degrees C to volts.
A strange but functional tire-pressure warning system, based on wheel rotation speed differences. Provides a rather entertaining display.
A simple and robust way to mount a GPS power cradle using the vent-panel as a base, which puts it in a good position for both driver visibility and receiving a wide sky's worth of satellite data.
Installing cruise control, hybrid gatherings, and other stuff.

Emergency power
One of several efforts to use the Prius as a home generator / UPS.
Crocking together a collection of parts to charge a spare Prius hybrid pack and run a UPS from it, during some slack time at Tour de Sol. It made a great albeit slightly dangerous demo.
Another UPS / generator project, with up to 1 KW capability [but that does draw a *lot* of current from the 12V system].
Yet another method of tying in a UPS. The 450VA Best Ferrups has 66 Ah at 12V inside, way more than the Prius aux battery itself. The right answer, however, is to stop messing around with this feeble 12V nonsense and build a 10kW or more inverter that feeds directly off the HV battery. But see below...
And my own long-term rig: a 3 KVA "plug-out" system installed -- a bit of a compromise in many ways, but meets my needs for now.
Mac Mini integration to onboard display screen.
Mostly-Japanese sites; pointers to several other Japanese-only sites. Worth a look even if you don't read Japanese; the project pix tell quite a bit about what people there are hacking on. The latter site is where "Ken@Japan" details his SuperMID instrumentation projects.
A hilarious and very down-to-earth look at electric vehicles and surrounding environmental issues from a woman's standpoint. Lots of good links to other resources about electrics, batteries, hybrids, and alt-fuels.
More Prius links and discussion from the point of view of an Insight owner. Documents easter-egg dances for user-settable things such as reverse beep. Check out the rest of too, it's quite interesting as another plug-in Prius mod clearinghouse, and getting more extensive all the time.
Simple guide to removing the lamps in the door "courtesy" lights in order to avoid excess 12V battery drain. Includes a means of amply compensating for the safety aspect of disabling the lights with "reflective bling".
Darelldd's extensive Prius mods/hints/fun pages, from the perspective of a guy who's been driving solar-charged EVs for several years and is really into LED lamp replacements and many other energy-saving projects. Darell is also quite active on Priuschat.
Four new Michelin "Green-X" Energy Saver tires installed on the Prius in late 2009, using metal bolt-in valve stems instead of rubber and taking the opportunity to document the whole process.
A PHEV conversion in the UK, whose builder Nikki has valiantly pressed on despite at least one hopelessly overcharged pack and is definitely still in there doing it ... for SCIENCE!
Some silly "photochopper's concept" ideas (ahem) on how to paint up the plastic trim rings for different effects. Frankly, it seems like simply pulling them off is the best approach.   [long URL!]
Funny Prius pseudo-ads by David Krulik, involving hookers and dead bodies.
Adventures in "debadging" a Prius, and minor bodywork/painting artistry to de-emphasize the blank areas left behind.
Another personal collection of hacks to a 2002 Prius.
Collages of three years' worth of "slideshow" -- reflecting all the fun to be had with hybrid vehicles, their tech, and the community around them.
Home-made OBDII interface info.
Links and support for "MegaSquirt", a complete, open-source EFI system that you can build, calibrate, and tweak yourself. Unrelated to the Prius specifically, but great reading for learning about fuel-injection systems in general.
One person's EV conversion chronicle.

Network miscellany

This is only a tiny sample of the Controller Area Network and other data network info that's floating around out there. Attila Vass, in particular, has some good info about pulling realtime data off the CANbus in the '04 and up Prius; the equivalent of the miniscanner for the "classic" is a likely result. The "Prius_Miniscanner_MarkIII" yahoo-group also exists but doesn't have public archives.
Attila's CAN project.
can232 / serial converter dongle[s] ; USB soon.
Low-level CAN protocol documentation from Kvaser.
Their (outdated) copy of the original BOSCH spec can be directly accessed here:
Other files in their download area hide behind a similar syntax if you don't want to deal with their silly intrusive request form.
Using a simple switch box to isolate a separate chunk of CANbus from the car so that scantool requests can be analyzed, to a degree. Has details on how OBD-II protocol is encapsulated inside CAN and some of the specifics on collecting data from the ECUs in a Prius. Uses the manufacturer-specific data item for fuel injector time as an example, and why that is a particularly good parameter to monitor. A companion file sgpkt.txt breaks out the CAN packet protocol and the encapsulated ISO15765-2 queries/responses inside.
CAN in Automation news and standards/specifications site.
CAN chipsets and stuff.
AVC LAN and other car-audio stuff from Fujitsu Ten.


Various U.S. patents relating to the Prius, filed by Toyota to mirror the Japanese patents. If freepatentsonline is unreachable, check Basically, any time Toyota says "power output apparatus and method of controlling the same", they're talking about hybrid drivetrains.
Effectively the "master" Prius driveline patent. Covers all possible operational modes and control of the engine-plus-two-motors system.
Battery charging control.
Canceling battery "memory effect" via infrequent wider charge/discharge cycles.
Regenerative drivetrain torque control, including engine jake-braking mode.
Electronically-controlled braking system.
Braking control in general.
Regenerative/electronic braking fail-safe mechanisms.
Engine start/stop via the two motors and power split device.

Other patents

A few non-Toyota patents that are nonetheless interesting from an energy-conservation standpoint.
Hydraulic energy storage for hybrid vehicles [concept].

Can't find something? Google is your friend, even if they do keep big-brotherly details on what you surf.
[Reading the HTML source may turn up a couple of other surprises, too.]


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