By on February 23, 2009

Danny Westneat at the Seattle Times apparently wasn’t taken in by the “This Car Gets 100/150MPG!” signage on Seattle’s test fleet of plug-in hybrid electric vehicles (PHEVs). And it seems that his journalistic incredulity was rewarded with some disappointing numbers from Seattle’s real-world testing of the much-vaunted PHEVs. Sure, a converted plug-in Prius might get 100 mpg in the hands of a fanatic hypermiler, but in daily use by untrained city drivers, the PHEVs return much more moderate results. Westneat reveals that Seattle’s 14 plug-in Priuses actually averaged about 51 mpg after driving a total of 17,636 miles in all kinds of conditions. And the Seattle case is no fluke.

Google’s “Recharge” fleet of PHEVs returns similarly underwhelming results on average, specifically 37.7 mpg from a plug-in Ford Escape and 54.9 mpg from several plug-in Priora. Now, clearly 37-55 mpg is an improvement over their standard hybrid equivalents, but with Prius PHEV upgrades retailing fom $10K and up the cost of plugging in works out to around $1K per mpg improvement. According to Westneat’s math, even if battery prices were cut in half PHEV Priora would have to hit 80-100 mpg to overcome the shocking plug-in premium. And that’s not great. Are PHEV’s evolving technology? Sure. Will changes in driving style help improve those numbers? Probably. But does slapping “This Car Gets 100 MPG) on the side help the cause when those numbers don’t translate to reality? Not so much.

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22 Comments on “PHEV Letdown Begins...”

  • avatar

    51 MPG isn’t bad, but, yes, if they advertise 100, you’d expect to get that much doing untrained, unrehearsed CITY driving.

    As a resident of NYC, City driving estimates are all that matter to me.

    I think the Ford Hybrid’s and EV’s are going to do really well this year and next – lots of rave reviews on them and they are only getting 35mpg CITY.

    If Chrysler wants to succeed, they really ought to make a 300, Sebring and PT cruiser that get 35mpg or better because on the market as it is, NO OTHER CAR MAKER has as much interior space as Chrysler does. The only other car with as much hip, leg and shoulder space as a 300 is the S-class. Many other car companies claim to have more but their seat cushions, side walls and rooflines take away alot. A Chrysler – any of them – is like driving around in a boat.

  • avatar

    «$1k per mpg improvement»

    At $2/gallon, it only takes 1,000,000 miles per vehicle for Seattle taxpayers to start making a return on their tax investment!

    Each Seattle PHEV will save 36 tons of CO2 over that 1,000,000 miles. Then again, CO2 offset websites will sell you 36 tons of Carbon Indulgences for $504, so Seattle taxpayers are only overpaying their CO2 sins by a factor of 20 —it would have been 20 times cheaper to buy carbon offsets than to convert the Piouses to plug-in.

    Congratulations are in order, methinks. Each $ paid in sales and property taxes should be enjoyed that much more.

    Cheers, Seattle taxpayers and Google shareholders!

  • avatar

    I think we know why Toyota didn’t make the Gen II Prius a plug-in hybrid.

    It’s all because Toyota engineers and managers can do math! What a neato skill to have!

    They’re so advanced, it’s daunting. However, it is my sincere hope that eventually we consumers will learn this valuable skill for ourselves.

    I really look forward to the day when I can calculate my own “break even” point. It would be a bonus if I learn how to figure out how many eggs and how much sugar and flour to use when baking a cake or cookies.

  • avatar

    My 27 year old Yamaha Motorcycle gets 52 around town and 68 on the highway.
    Total investment around 600 bucks.
    It IS great to be able to do math.

    Plus the insurance is only 40 dollars a year and it hits 60 mph in around 4 seconds, is a snap to park, simple to repair, easy to maneuver around traffic jams, only requires two tires instead of 4, and no one asks to borrow it for carrying anything.

    Me thinks if you really want to save money saving money there are more conventional ways to do it. You can get a used corolla or an escort for around 1500 bucks that gets mid 30s or better on the highway. Without spending 20-48K and having to plug it in all the time.

    But what do we know, we are not the really smart people in Washington that are calling the shots these days

  • avatar


    You should probably relax. From (some other source, I didn’t save the link):

    “Thirteen Toyota Prius gas-electric hybrid vehicles owned by Puget Sound governments and agencies will be converted to 100 mile-per-gallon plug-in electric hybrid vehicles for a year-long field performance test, in part with a grant and technical assistance from the U.S. Department of Energy’s Idaho National Laboratory. Behind-the-scenes assistance from Discovery Institute’s Cascadia Center for Regional Development played a key role in development of the pilot project (more below).”

    Turns out they got a grant. To study it. Now it has been studied. Mission accomplished. Someone was going to study it and if it turned out to save a lot of fuel, the city would have been well ahead.

    Elsewhere, a different test PHEV fleet (in Europe, I think) was found to get 67mpg. Toyota’s still going to be interested in this technology. GM is gambling a lot of money on a closely related idea.

    A PHEV that works well could save a significant amount of oil and abate a significant amount of GHGs. Maybe the 67mpg test reflects something interesting. Maybe 51mpg will turn out to be more typical.

  • avatar
    John Horner

    From the Seattle Times piece: “Try 51 miles per gallon, city and highway combined. Not counting the cost of the electricity.”

    51 mpg for the fuel used PLUS some un-tracked amount of electricity consumed. Plug in hybrids remind me a little bit of flying cars. Neither a good plane nor a good car.

    The extra weight of bigger battery packs makes these things use more energy to get up to speed and probably results in the friction brakes being called on for a larger fraction of the stopping action. So you loose when getting up to speed and don’t get as much regenerative braking on the way back down.

    Hybrids optimized for gas-only use show a lot more promise than PHEVs do at this point.

  • avatar
    George B

    I doubt that PHEVs energy cost savings can ever cover the extra battery cost, but this article and the Seattle Times article make no mention of a control group for the study. What was the gas mileage for an unmodified Toyota Prius in the same fleet driven under the same conditions by the same drivers? What about fuel economy for other vehicles? It’s possible that when somebody else is paying for the fuel, drivers will tend to have a really heavy right foot.

  • avatar

    «Turns out they got a grant.»

    Not cool.

    So it is not the Seattle taxpayer who is overpaying 20 times the benefit…

    It is all federal taxpayers. That would include me.

    Somewhow, I don’t feel any better.

  • avatar

    100mpg would be great, but the best return on the investment is by focusing on the low hanging fruit. Going from a car that gets 20mpg to one that gets 40mpg saves nearly three times more gas than going from a 50mpg hybrid to a 100mpg super hybrid.

    Even adding a little air in the tires of the old Suburban and fixing the worst holes in the gas tank, so it gets more 12mpg instead of 10mpg saves more gas than going from a 50mpg to 100mpg!

    Seems counterintuitive, but some quick math revels the truth.

    15K miles a year, 1500gallons at 10mpg, 1250gallons at 12mpg, savings 250 gallons.

    15K miles a year, 300 gallon at 50 mpg, 150gallons at 100mpg, savings of 150 gallons.

    Aggressively working on getting the majority of the fleet to the 40-60mpg range seems more important thing for now than playing with 100mpg niche vehicles.

  • avatar

    Uh-huh. Anyone who starts doing the math on these high-mileage cars will soon see that the payback for the premium price they command is very long indeed. Actual math won’t matter to treehuggers, and that’s OK. But it’s why I didn’t buy a Prius in 2005, but opted for the Scion xB instead. I didn’t care for the 12-year payback for the extra $5000, not to mention the added complexity of a hybrid vehicle.

  • avatar

    From EAA-PHEV website. Although we know they are a bad idea, I have to acknowledge that the authors don’t hype the idea and do lay down comprehensive details on the pitfalls that Prius PHEV conversions have in store.The following is for a 2006 lead acid conversion…….

    “Though we are using the best and most cost-effective PbA (lead-acid) modules we could find, a PbA PHEV is neither economically nor operationally up to par.
    Prius-forced limitations

    This conversion will no doubt void parts of Toyota’s warranty. U.S. law prohibits aftermarket modifications from voiding any part of a vehicle’s warranty except for problems specifically caused by the modification.

    If repair of the OEM battery, transaxle, or other parts of the hybrid system becomes necessary, Toyota may will argue that the PHEV modification has caused the problem. The outcome is uncertain, see also our Warranty article.

    EV-only mode (which inhibits ICE operation) works only up to 34 mph, 120A of power (modest
    acceleration), and a few more obscure limits

    When the Prius starts the ICE for the first time after being turned on, the ICE must warm up for several minutes before EV mode can be re-entered. This process burns more fuel than normal.

    The charge / discharge limits are affected by the temperature of the OEM battery.

    PbA limitations
    The conversion adds 300+ lbs to the vehicle’s weight to provide 10 miles of electric range per charge (16.7 usable Wh/kg)

    Though I have safely driven 17,000 miles in my converted Prius, the added weight could possibly cause vehicle instability during driving, and the battery may modify the effectiveness of the vehicle’s rear crush zone.

    Existing conversions sit 1-2 inches low in the rear. Air shocks or heavier-duty rear springs would be nice, but have not yet been developed.

    Though there are indications that improved hybrid efficiency due to a lower combined internal resistance of the two-battery combination at least partially compensates for the added weight, city gasoline mileage is otherwise reduced by up to 10%.

    Operating costs are high due to an expected cycle life of only 300-400 deep cycles, providing only one to two years of daily driving (at 400 cycles, 10 electric miles per 2.1 kWh cycle, and $800/pack, battery cost is $0.95/kWh throughput or $0.20/electric-mile (in addition to the cost of electricity, usually 2-4 cents/mile depending on utility rates).

    For decent battery life, the battery must always be charged within a day of discharge, making charging a required rather than optional operation (if planning to drive to somewhere without access to electricity, temporarily turn off PHEV operation).

    PbA batteries perform very poorly in cold weather. Though our design includes a thermally insulated battery pack, heated during charging, this feature has been insufficiently tested due to moderate California temperatures during development.

    SafetyPotentially lethal voltages are involved. It is important for the high-voltage wiring to be done by an electrician or an engineer experienced with high-voltage safety.

    Once the conversion is complete, all high voltages are inside screw- or bolt-secured areas, but these areas are exposed during parts of the conversion process, during battery replacement and other servicing, and possibly after a crash.

    In keeping with hybrid automotive standards, high voltage cabling is labeled with orange (as #4 gauge and larger orange wire is not readily available, we specify the addition of orange shrink-wrap at each end)

    This design should be adequate to contain the batteries in any normal driving conditions, but extreme or off-road maneuvers could damage the installation, potentially causing a hazard.
    More importantly, though we believe the parts are well-secured, we are not automotive design engineers, the design has not been crash-tested, and its characteristics during and after a crash are unknown. In particular, it is uncertain whether the battery box would remain intact and in place during a roll-over incident.

    PbA modules could tear out of their brackets and
    fly around the passenger compartment

    Though these AGM PbA modules are not flooded, they could leak acid if crushed.

    Short circuits could arise, causing sparks, hot, molten metal, and possibly igniting a fire.

    The battery pack may modify the characteristics of the vehicle’s rear crush zone. “

  • avatar
    Rev Junkie

    Of course, the greenies will argue that the premium for PHEV conversion is worth it because they are “saving the planet”, not to mention they can lord it over lesser Priora with big-ass stickers slathered all over (think GMT900 Hybrids, only worse).

  • avatar

    I got screwed by another hypermiler yesterday. I was waiting for traffic to pass to make a left, he pulls onto the road during the small opening left between lights and proceeds to glide towards the light at maybe 3mph (slower than a walk). This manuever blocks me from crossing, and I had to wait another 20 seconds or so (as did the 3 cars behind me). Big deal? Yes. It’s insanely rude and inconsiderate to drive like that. The usual problem they cause is keeping many people from being able to make the next light without breaking, and thus having to reaccelerate.

    I suppose if you are doing it to save your own money, then it’s rational, but don’t act like you are saving gas because all the people idling and braking around you are wasting much more than you are saving.

    If you want to hypermile, go ahead, but try to be aware of the others on the road around you.

  • avatar

    A ticket for “obstructing traffic” might make some sense.

  • avatar

    «If you want to hypermile, go ahead, but try to be aware of the others on the road around you.»

    I must admit I haven’t noticed any overt hypermilers in my 6-mile daily Miami commutes —at least not the one-car in front of me which is what I might be able to see and differentiate from regular old heavy traffic and unsynced stoplights.

    It might be amusing to see them the first time or two but they might cause road rage if they proliferate!

    Are they common elsewhere?

  • avatar


    In all fairness, like many other things in life, a handful of douchebags give the rest of the group a bad name. Most hypermilers are not that inconsiderate. I, for one, will not get in the way or endanger anyone to squeeze out an extra half mile per gallon. It’s just not worth it. If I can’t safely coast up to a light, I won’t do it. It’s not a difficult thing to think about, but again, there’s some people that just try so hard that they make things worse.

    Doing nothing extra besides sensible, conservative driving (it’s not a race, and they’re called speed limits) can give everyone 15% better fuel economy, without being rude or dangerous.

  • avatar

    Normal priuses get around 50mpg. So this plug-in thing, uh, WHERE’S THE BEEF???!

  • avatar

    I’m already getting 48 mpg in my TDI. It doesn’t look like this is ready for primetime yet.

  • avatar

    3 mph isn’t hypermiling. It’s wasting gasoline. You want to get up to 20 mph, then shut off the engine and coast. ;)

    51 mpg… plus the cost of electricity? Dear lord, I nearly choked when I read that line. Here’s a thought. Why don’t we chuck out the insanely expensive hybrid drivetrain and run the whole thing on electricity? I can get 50 mpg in a diesel. And before anyone interjects to say “clean”, the amount of fuel you use is directly related to CO2. Anything getting 50 mpg is emitting the same amount of CO2. No, wait. If that’s 50 mpg plus electricity, that’s 50 mpg’s worth of carbon emissions plus whatever emissions are generated to generate and transmit the electricity used.

  • avatar

    I’m no expert on these conversions, but I would have to think that this test isn’t representative of what a purpose-built PHEV can really do.

    For one thing, the converted Prius still only goes up to about 35 mph on electric propulsion only… and that’s likely only in a situation in which a driver is driving conservatively. Given the driving habits of a bunch of government drivers who aren’t paying for their own gas it’s unlikely they were getting the best efficiency.

    A series-hybrid plug-in, on the other hand, can theoretically go faster on electric propulsion, thus making the first 30 miles or so of daily driving gasoline free.

    Of course, one still has the added weight and complexity of the two systems and batteries vs. a pure battery-only EV.

    I would think that the most efficient would be a pure plug in optimized for commuter duty and a second light-weight efficient gasoline or better, Diesel-powered vehicle for the occasional longer trip.

    In my household, my wife and I each have our own cars… hers a Mazda5 used for family trips and kid-hauling duty. My car (a 1994 mid-sized Mercedes convertible) is usually relegated to local commutes, driving my son to school, and local errands. Like many families, I bet I could make due with one of these cars as a plug-in EV with a range of 50-60 miles. Of course, I’d like four seats so the whole family can pile in, but otherwise I have another car for longer trips.

  • avatar

    stevelovescars makes a good point… a purpose-built PHEV, as opposed to an “upgrade” is likely to perform differently (and, we hope, better).

    Also, I noticed that Google’s fleet of plain-Jane Priuses gets 42.8mpg while their PHEV’ed Priuses get 54.9. That’s actually a significant improvement. There are lots of unknowns, of course (are the cars driven in similar or different ways, etc) but, on the face of it, it’s a significant improvement for the upgrade.

    niky, Mostly, electricity to move a car a mile is much cheaper than gas to move a car a mile.

  • avatar

    Cheaper. But better if it’s electricity only, and not gas. Let’s break the numbers down:

    At 54.9 mpg, you’re using 4.28 liters of gasoline for every 100 kilometers ( l / 100 km is an excellent way of looking at consumption from a cost perspective).

    At 42.8, it’s 5.49 l/100km.

    So, that’s 4.28 l versus 5.49 l. A 1.2 liter saving per 100 kilometers… or about 1/2 gallon every 100 miles, in the same driving conditions.

    That’s what I love about the l / 100 km. It shows you exactly how much that all means in the real world.

    The improvement is slight… but we haven’t gotten to the best part yet… Nobody is telling us how much electricity is used to offset that 1/2 gallon.

    I’d prefer a purpose built EV… period. Maybe add an IC motor for emergency charging or to for emergency mobility… but an onboard charging motor doesn’t have to be big enough to move the car at freeway speeds. A sad step backwards for the Prius is the inclusion of a larger 1.8 liter engine in the new model. It’s simply not needed.

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