Check out the Dell Store on CNETEPA confused by Chevy Volt's fuel economy
(Credit:
General Motor Co.)
The EPA is not sure how to rate the Chevrolet Volt's fuel economy, and GM isn't at all happy about it.
According to Motor Trend, the confusion stems from the EPA's classification of the Volt. Is it an electric vehicle (EV) with an onboard generator, or a hybrid vehicle that relies heavily on its electric drive? It's actually a little of both and a little of neither. The driving habits and battery-charging routines of the operator play a huge role in the classification of the Volt.
The way the Volt is designed, the wheels are powered by the electric motor and lithium-ion battery pack. When the batteries run low, the gasoline engine kicks in to extend the range. There is no direct connection between the internal combustion engine and the wheels. If the driver's commute is longer, driving is more aggressive, or if no plug-in option is available, the Volt will have to use its gasoline engine to keep the batteries charged, behaving more like a hybrid in this scenario. If the driver has a short commute, takes it easy on the accelerator, and plugs in to recharge the battery during the day, the Volt will operate primarily as an EV, and the gasoline engine's role will be greatly diminished.
In this configuration, the Volt can slip through about 85 percent of the EPA's test cycle without even firing up the gasoline engine. Using the EPA's standard formulas to calculate fuel economy, the Volt averages over 100 mpg. The EPA doesn't think that astronomical number is fair and has revised its tests with the requirement that the Volt finish the test with its batteries close to full charge, which means the internal combustion engine must run for the entirety of the test, dropping fuel economy to about 48 mpg.
GM, of course, argues back that the EPA's new test isn't fair because the test isn't representative of the way the Volt was designed to operate and doesn't reflect the Volt's plug-in option for battery charging.
The truth lies somewhere in between, but the EPA rating assigned will play a big role in whether consumers think the $40,000 Volt is a good deal compared with the Toyota Prius and the upcoming, and even less expensive Honda Insight.
p.s. these are just broad questions I would like to see answered. Whoever is more up to speed then me, could you please fill me in. Thanks.
This is a new kind of car and using the same old rating system would be totally unfair. If this thing rolls out with a 48 MPG sticker it will be an instant failure. People will compare it to the 50 MPG Prius that costs half as much... which would be stupid because the Volt has the ability to use no gas at all for long distances. In fact GM says it's 40 mile range is enough so that most Americans wouldn't need to use any gas at all over the course of a day.
I also have to agree that most people's commutes are nowhere NEAR 40 miles both ways. My parent's is, but then again they want to work for a big hospital in the city while living in the 'burbs. For my commute, when I was working outside of home..... no, the 20 mile distance each way would be 4 times what my commute actually was.
In that case, perhaps the EPA should also average out the fossil fuels used to generate electricity in many states and apply the numbers to the Volt's MPG. I'll trust the EPA's science over GM's marketing department any day.
I propose a simple approach: The sticker should have, say 5 MPG ratings for trips of increasing distance: trips up to 20mi, 40mi, 100mi, >100mi. Each driver knows which applies to him... and can make a decision accordingly.
I don't hold out any hope that those Govt workers will figure this one out. Someone said they were actually using their mileage test loop. What brainless dolts!!!
If you are looking for MPG then the battery pack needs to end the test at the same charge it started - otherwise you get inflated MPG results. It's the same as starting the test at the top of a hill and finishing at the bottom. The car has two sources of power - electric or gas. MPG is based on the gas used to propel it as the total source of energy consumed. The obvious criteria for the electric mode is how far you can go before you start thinking about the MPG. Two sets of numbers for the window sticker: Standard EPA MPG and Pure Electric Range. Keep the same EPA tests and just report these numbers.
Honestly though, the Volt is getting too much credit for being advanced when it is simply a modern component production version of the 1970's Subaru conversion in Mother Earth News. At least the Prius and Insight added some new concepts.
The test should be full charge and full tank. Run the Test Loop, City and Hwy, until its out of energy. Recharge the Car monitoring the kWh consumption. Refill the tank. Convert the gas usage to kWh. It's about 38kWh/gal. Take miles driven divided by the sum of the energy to charge the batts and the gas. and Poof, mi/kWh.
pjm237 I agree with that, thats the best way to do ratings when we start mixing up this kinda stuff, only thing I see is the need to put the avg 38kWh/gal gas on the sticker too. Though that in its self presents an issue because every car will have a different avg so you cant just say 1 gallon = 38 kWh.
Even the Prius struggles with justifying its added costs compared to a regular economy gas engine.
Does GM not get? The rich who can afford a $40,000 car don't care about paying for gas.
Its the poor people who need to save gas!! They certainly cannot afford 40 grand for a vehicle that will not save them any money for years!!
I myself would love a series hybrid with an engine that can be easilly taken out when not needed for extended range. Keep the generator at home. Even hook it up to power your house when the power goes out. I want to only use the engine when I want long range, on trips. For 95% of my use I want to be able to run pure electric.
total miles driven to no charge and empty tank / size of tank in gallons = x mpg
whichever is used (gas or electric) the majority of the time of the test designates which kind of car it is (or some similar simple formula)
sounds like someone (GM) knew the results ahead of time and "studied to the test"
Now there are at least two different dollar cost factors and two different environmental cost sources. The dollar costs are gasoline and electricity prices, and the environmental costs are tail-pipe pollutants and electrical power plant pollutants.
The first casualty in this situation is that the environmental cost per mile, which is the true business of the EPA, is no longer representative of the dollar cost per mile. So the model will probably have to be overhauled, or scrapped and rebuilt.
What will come of this, it seems to me, is that there will be two numbers, DPM (dollars per mile) and PPM (pollution per mile). And these will probably be ranges. We're used to this with the City / Highway ratings for MPG; there will also be a range for the combined efficiency of the battery (charge-discharge) and the motor. And maybe the drive chain? Better stop now. Brain cloud forming.
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by EVehicle
September 12, 2008 8:29 AM PDT
- DOE's Advanced Vehicle Testing Activity (AVTA), INL, and testing partner Electric Transportation Engineering Corporation initiated Plug-in Hybrid Electric Vehicle (PHEV) testing activities during the second half of 2006. The link below will take you to the site where results are posted on some of the existing PHEV conversions. The results shown under PHEV America is the best source for comparison of not only fuel economy in both charge depleting and charge sustaining modes but also the kWh electricity comsumption as well. I expect that this testing program will also evaluate the production PHEV products coming as this was also done with production battery electric vehicle under the EV America banner in the past. Real vehicles on real roads driven by real people. The test procedures used produced excellant and meaningful results. This is the information that consumers can use to make informed, intelligent choices.
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