REPORT: 115 Plug-in Priuses fail to crack 50 mpg average in year-long test
When Consumer Reports tested out the Hymotion L5 plug-in Toyota Prius conversion earlier this year, they weren't overwhelmed with the results. Sure, the mileage they observed was boosted to about 67 mpg over the first 35 miles of the drive, but that didn't match the claims of 100 mpg (or more) that Hymotion and A123 Systems make about their product. To be fair to Hymotion, their qualifies mileage talk about their plug-in Prius MPG "that can achieve up to 100 mpg for 30-40 miles" this way:
Hymotion PHEV fuel economy is based on independent testing performed at Argonne National Labs and Idaho National Labs. Actual mileage will vary based on each individual's driving style, route, traffic, climate conditions, terrain and other factors.Unfortunately for Hymotion, there are new results of tests done at the Idaho National Laboratory now available and they might make the company a little less eager to promote the work done by INL. The lab drove two groups of Prius test vehicles (one 40-car fleet and another 75-car fleet) from early 2008 until March 2009 for almost 500,000 miles and found that the average fuel economy tallied 46 and 49 mpg, respectively. As you might expect, driving style and the battery mode (charge sustaining vs. charge depeleting) had a big impact on the figures. You can view the result data in these PDFs: 1, 2. Sounds like PHEV proponents could take former Tesla marketing boss Darryl Siry's advice to electric vehicle manufacturers to heart.
[Source: Idaho National Laboratory, Greg Blencoe]
Reader Comments (Page 1 of 2)
Snowdog 1:01PM (6/15/2009)
I have always stated these conversion kits are a money waster and there is much to criticize here:
The Prius is not well suited to be a PHEV, the motors are not set up/powerful enough to allow full scale highway speed EV operations.
I am also dead set against making MPG claims based partially on some arbitrary number of charging cycles. Such claims should be dismissed out of hand.
Hymotion battery packs are only 5KW, less than 1/3 of a Volt. So perhaps 1/3 the added EV range ~ 13 miles. Saving at most a 1/3 gallon gas per charge. Also significantly less that the 40 miles stated as something that would cover typical daily usage.
BUT. This isn't a general indictment of the PHEV/EREV concept as painted by Blencoes FUD.
But the minimum point of entry has to be (IMO):
An EV drivetrain that will drive the car in all conditions, allowing it to run significant distances in EV mode.
A EV pack that will cover the most of the user daily MPG. Say 40MPG like the Volt. But further the user needs to be rational. If you drive 200 miles per day. A Volt is a waste.
When you have this and actaully put them in drivers that make sense for the EV range, you would see much more Gas saved.
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gorr 1:10PM (6/15/2009)
I knew it that the prius was an underpowered build-in mandatory hypermilling car that nobody like and this transformation from ignorant zealots just jack up the price, LOL. Engineering is engineering and all green cars of today are sh*t, nothing else. Even the water car proponents and experimenters are a joke with huge lack in the carburation convertion process.
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FitFan 2:43PM (6/15/2009)
Go back to school.
Chris M 5:15PM (6/15/2009)
I must be a "nobody" as I like the Prius, and there are a lot of other nobodies out there, as Toyota has sold over a million of them.
Gorr, it is silly of you to criticize the engineering, as you can't do it, either.
Ernie 6:05PM (6/15/2009)
"Even the water car proponents and experimenters are a joke"
I hold this up as a prime example of what makes Gorr a frickin' idiot. It's not "even" the water car proponents and experimenters, it's *especially*. They may as well be trying to develop perpetual motion because what they're trying to do defies the laws of physics.
But since Gorr never took even high school physics, he wouldn't know what engineering was if it kicked his ass and took his paycheque. He's one of the "worst of us" who is so convinced his opinions are right and will shout it from street corners.
gorr 10:17AM (6/18/2009)
I said that water car proponents and gazeous hydrogen car builders like bmw or ford are lacking on the carburation engineering. Gazeous hydrogen is not carburated like air/gasoline. Especially water car proponents and experimenters are a joke, they even don't know the basic carburation process. Ford and bmw are limp too in that domain and they feel it that they are limp and under-performing without on-board hydrogen production and no water re-circulation and unnessary huge hydrogen tanks with fueling problems. They are still not offering hydrogen cars or small trucks to normal paying consumers. Consumers leaded by me are waiting to buy a green car for cash that they will own. Since the 1990's every car-makers along with high financial circles have wish to steal all money and business and taxation and deseases and refuse to sell cars for cash, only false credit contract are offered, if not the manufacturer is put on bankrupcy. So every big car manufacturers have accepted that and betray each and every of his customer to stay in high financial regulations and privite taxmoney gimmicks. That's why there is not a single green car on the market, it's because of gm, toyota, volkz, etc. They have been bought by taxmoney to keep petrol gimmicks and kill the biosphere along humanity. It's the work of goverments to do so, collect money to kill humanity by securities gimmicks. They even study flu and viruses and the commercialization aspect of it.
Rav4-EVer 1:18PM (6/15/2009)
My wife has a Hymotion in her Prius. She drives exactly as she did before (she does not try for good mpg) and she gets about 80...sometimes a little higher,obviously lower when she goes on a road trip and can't charge it.
When I drive it around town, it is rare for me to get less than 100mpg. I shoot for good mpg, but I stay out of traffic's way. On one 30-35mph low-speed trip on flat ground, I got just under 1000mpg.
Of course a factory PHEV could be better, but there are still none available, and we have had this for over 9 months. Electric cars are better yet; I am driving a 6-year old RAV4 that is awesome for around town...but with a 100-mile limit, we need to keep the PHEV around.
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paulwesterberg 1:40PM (6/15/2009)
Fleet drivers are probably not used to driving evs to maximizing mileage. Idaho falls(and montana/wyoming) where this is located is pretty sparsely populated so they probably put on a lot of highway miles which is not really the ideal use for a prius, let alone a plug in conversion with only 5kWh of batteries.
Hymotion++ 8:45PM (6/15/2009)
We upgraded my wife's Prius with a Hymotion rig a couple of months back and I agree with Rav4-EVer. She has averaged 75-80mpg per tank since then since she is mostly an around-the-town driver. We have also seen an increase of 5-10mpg on the highway which surprised me. The biggest disappointment has been that there is not an EV button on the car. A real miss IMO.
I think if you are a leadfoot foot (like the uninformed gorr here) then you might not see much of a different but if you pay attention, the Hymotion configuration can save a significant amount of gas (and pollution, and foreign oil dependence, ...).
Then again, I'm still looking forward to my converted Yaris from EVInnovations.com.
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lawstud 12:58AM (6/16/2009)
http://www.google.org/recharge/experiment/
The hymotion battery pack in a Prius averaged 93.5 miles per gallon combined. Highway driving went from baseline 53.1 mpg to 68.7 mpg.
Depends on city and highway driving. The more city driving the higher the combined rating.
Note: modding the prius to drive all electric up to 64mph is possible:
http://www.greencarcongress.com/2009/06/picc-20090610.html (although they claim 70mph, the video doesn't show that, only 64). Note they've driven 4 minutes at around 60 mph and the battery depletes 20%. at 5% depletion per mile on their 6.1 kWh battery pack they'll get 20 miles if they completely discharge the batteries. Doing so and needing a replacement within about 2-3k cycles if they're using cheaper Chinese lithium ion cells. If they don't fully charge or discharge the batteries last longer, which is why the volt has a 16 kwh battery pack but only 40 miles, they don't fully discharge or charge the battery pack. i.e. they still need to develop batteries for electric cars. Lithium ions are a gapfiller in the meantime.
The hymotion battery pack is only 4.7 kwh.
64 mph is also what Toyota's plugin prius test vehicles get when they doubled the battery pack and they altered the programming (according to popularscience article about it.)
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Dave 2:41PM (6/15/2009)
What a crappy summary. Here is some vital information for those who haven't read the PDFs. Fuel economy numbers reflect the 40-car fleet first and the 75-car fleet second. CD = Charge depleting, CS = Charge sustaining
1. CD trips: 62 mpg / 62 mpg
2. CD/CS trips: 49 mpg / 52 mpg
3. CS trips: 39 mpg / 43 mpg
25-30% of miles were in CD mode.
22-28% of miles were in CD/CS mode.
47% of miles were in CS mode.
Fuel consumption was about 34% lower in CD mode than CS mode.
Average distance between charges was 34 and 41 miles. Way too far for the size of the installed pack which will provide at most about 10 miles of "EV" miles.
So it's quite clear that the Hymotion pack met expectations once you look at all the numbers.
It's also quite clear that there is a lot of room for improvement in drivers training, pack sizing and charging opportunities.
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downtoearth 5:24PM (6/15/2009)
Thank you very much for this summary, Dave.
The "Charge depleting"(CD) mode is probably the only one which is significant since batteries are charged with purpose of depletion and electric assistance of the internal combustion engine so that it burns less fuel. Any other way makes little sense to me.
The article key suggestion...
Sebastian Blanco:
> The lab drove two groups of Prius test vehicles (one 40-car fleet
> and another 75-car fleet) from early 2008 until March 2009 for
> almost 500,000 miles and found that the average fuel economy
> tallied 46 and 49 mpg, respectively.
... has to be somehow misleading as these are the mileages that drivers of ordinary Prii II without any convertion get:
http://fueleconomy.gov/mpg/MPG.do?action=browseList2&make=Toyota&model=Prius
why not the LS2LS7? 8:38PM (6/15/2009)
Everything meets expectations if you set your expectations low enough.
The question is, is 10 miles (and not even that at highway speeds) enough to make a PHEV worth it? The answer here appears to be no.
Chris 4:21PM (6/15/2009)
Truth comes out that battery power isn't the technology for the future. It's not just this story but a collective of everything battery power. Batteries suck and everyone knows it. The sooner ultracapacitors and hydrogen come out, the better.
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Chris M 5:32PM (6/15/2009)
Chris, you're basing your opinion on one report that covers one application - and a rather limited application at that.
Batteries are more efficient than fuel cells, or any internal combustion engine, so why shouldn't it be "the technology of the future"? Tesla Motors has proven that performance is there, and range is no longer a big issue. Of course, there is plenty of room for improvement, new battery technology demonstrated in the lab indicates energy density could be increased 5x to 20x, making "thousand mile range" EVs possible, or perhaps giving reasonable range from a small inexpensive battery pack.
Fact is, the combination of batteries and electric motor is more efficient than any other power source, except directly powered electric vehicles like electric trains and PRT. The ultimate future transport is likely to be EVs that can also run on "powered guideways" for long distance travel.
AnotherDave 5:00PM (6/15/2009)
They are PHEV 10’s, what that means is that they are intended for short trips (10 miles) between recharges! If you drive a PHEV 10 for long trips they the get the normal mileage of a Prius carrying about an extra person’s weight. If the car was used for short city mileage trips of less than 10 miles and recharged between trips, then the car would get better than the 62 MPG listed.
I would like to see what the comparison is of these cars to a standard Prius, where is the control group?
Hello Greg Belncoe (and other hydrogen promoters), why don’t you provide a fuel cell system the exact same size as the Hymotion pack and prove fuel cells are better? If fuel cells are better, you should get better mileage. No cheating now, you have to include the energy that is used to generate the hydrogen gas or liquid and get it into the vehicle in the MPG equivalent calculations.
It would also be nice to know the energy cost of your system, since the MPG electrical costs are about a third of the cost of gasoline. The Hydrogen MPG are how many times more than the cost of gasoline?
Oh I would like to know how many more times the cost of the fuel cell system is over the Hymotion pack and remember your system has to be safety certified like the Hymotion pack is too.
The Hymotion pack is here now, how many years to you think it will take to get a hydrogen system ready to even try to replace it?
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Chris M 5:36PM (6/15/2009)
Well there was a Prius conversion that used H2 fuel in the IC engine, the conversion cost $70,000, which is a lot more than the Hymotion conversion, but that "H2 Prius" suffered from reduced power and a greatly reduced range of 80 miles. Not even remotely practical.
Dave 6:13PM (6/15/2009)
Not only are these PHEV 10s, but because of the limited amount of "EV" power in the Prius (about 50kW), if you exceed that and cause the engine to turn on, it will cause the car to go into "forced warmup" mode which burns extra fuel to fully warm up the engine and catalytic converter to minimize HC and CO emissions on future engine starts. Unfortunately, this has a detrimental effect on fuel economy. This is easily seen on stock Priuses where the first 5 minutes of operation very often reads about 25 mpg and subsequent operation is 45-50 mpg. The 2010 Prius has replaced the older coolant reservoir with a less complicated and more effective exhaust heat capture system to warm the engine more quickly when cold.
To work around the limitations of a converted Prius, either the Prius's generators/electronics need to be upgraded to produce more power and/or the drivers need to be trained to avoid triggering ICE start up unless it's absolutely required.
But either way - with 34-41 miles average between battery pack recharges and a battery pack only good for about 10 pure EV miles at the most, you can only cut fuel consumption down by ~25% in an ideal situation compared to the reductions of 12%-15% (for the 40-car and 75-car fleet respectively) leaves plenty of room on the table for improvement.
Terry Yeung 5:59PM (6/15/2009)
The title is a bit misleading. Reading through the report I think the important number is the mileage they got while driving in Charge Depleting mode. They got 62 mpg in both test fleets which seems to indicate it's fairly reproducible. I would be curious to know just how far they could drive their Prius in Charge Depleting mode if they start with a full battery.
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DasBoese 12:56AM (6/16/2009)
(Source: Greg Blencoe) says it all. Anything that comes from this EV-hating hydrogen zealot should be taken with a pound of salt.
I'm sure Blencoe popped a boner when reading this article, but if you care enough to actually hop over to the INL website, you'll see that he skewed the facts like he always does.
INL page:
http://avt.inel.gov/phev.shtml
Two articles ACTUALLY LINKED to from the INL website:
http://www.wired.com/cars/coolwheels/news/2009/05/plugins0506
http://www.greentechmedia.com/articles/read/are-the-benefits-of-plug-in-hybrids-overstated-6014/
From the first article:
"It sounds like they're not plugging them in," said Paul Scott, a founder of Plug-In America. "I don’t know how you would drive one and get such bad mileage."
"The results of these early fleet tests suggest EV advocates and automakers will have to tell people how to drive the cars most efficiently because they may not catch on if consumers don’t see the fuel efficiency they’re promised."
"You have to be impressed with what you're seeing," said Scott Thomsen, a spokesman for Seattle City Light. "Sometimes drivers are getting 100 mpg in a stretch. This shows what the vehicles can do in real world driving conditions, not a test track in the middle of Arizona with consistent conditions."
Thomsen notes the plug-ins are outperforming the city's conventional Prius hybrids by at least 11 mpg, so they're emitting about 25 percent less CO2.
"Seattle officials discovered the plug-ins were tooling around with dead batteries nearly one-third of the time. The cars with fully charged batteries got 50 percent better fuel economy than those with dead ones."
"EV advocates are quick to note the Prius wasn't designed to be a plug-in hybrid, and in fact makes a lousy one. The biggest problem is the electric motor is too small, so the car relies more heavily on the gasoline engine. Cars designed from the ground up to be plug-in hybrids, like the plug-in Prius that Toyota is working on or the Saturn Vue plug-in – will almost certainly offer far better fuel efficiency."
"We fully expect the performance of plug-in hybrids to improve as automakers bring original equipment to the market, but the bottom line question for the demonstration project is "Does this technology meet a person's transportation needs more efficiently?" Even at 51 mpg, The answer is yes."
From the second:
"What happened? For one thing, those drivers were just going about their own business instead of traveling only on designated routes in more ideal weather conditions. The tests were done in different types of terrains, and the results included mileage data from when the cars' battery packs were in use and after they were depleted. And those battery packs were not necessary fully charged before each trip."
"Accelerating quickly is a major no-no for getting better fuel economy. When you speed up quickly, it requires a burst of energy that takes more battery juice. Cranking up the air conditioning also will lower the fuel economy. So will conquering steep hills."
"But probably the single issue is: Have batteries been charged?" Francfort said. It isn't just about charging the battery in full before each day's use. "It may also be a lack of access to a place to charge, or of time due to job requirements."
Battery technologies matter, of course. The cars used in the program are converted plug-in hybrids, and the lithium-ion batteries are more experimental, said Tim Murphy, manager of the DOE program.
"That said, it doesn't hurt to create a tip sheet to train consumers to get the most of fuel savings from their plug-in hybrids, especially when companies such as General Motors plan to start selling them within two years.
That's what the folks at the DOE program are doing as part of its public outreach effort, Francfort said. He expects to complete the tip sheet in about two months."
TL;DR:
Driving habits and charge state of the battery have a huge impact on the mileage you get, and not telling people about this will lead to disappointing results. By golly, what a surprise! And with vehicles that were not designed as PHEVs, shocking I say, shocking!
The headline of the article should read:
"Some of 115 Plug-in Priuses fail to crack 50 mpg average in year-long test while others show remarkable improvement, depending on driving and recharging habits and driver education."
May I request that ABG never, ever, EVER take anything Blencoe reports at face value, ever? Please?
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