Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Quantifying the Volt MPG

This site may earn commission on affiliate links.
Cranking the Volt to 100 M.P.G. - NYTimes.com

First, the Volt is driven repeatedly on each E.P.A. test cycle until its battery is depleted to determine the number of kilowatt-hours of electricity consumed and the number of miles accumulated. Using an Energy Department Petroleum Equivalency Factor established for electrics and hybrids in 2000, the electric consumption is then converted to gallons of gasoline.

Next, the Volt is driven repeatedly on the same test cycle in its charge-sustaining mode, with the gasoline-powered generator, rather than the batteries, providing electricity. That yields a second set of gallons-consumed and miles-accumulated figures.

Now for the tough part: blending the total gallons consumed and miles driven together in some credible way to obtain final city and highway mileage figures suitable for posting on the Volt’s window sticker. Argonne’s intention is to use what it calls a utility factor, in essence a driving trip that consists of some charge-depleting miles and some charge-sustaining miles.

NY Times analyzes how the Volt might get that 100 mpg sticker - AutoblogGreen
 
Last edited:
Sounds like they are still debating what to do...

Argonne Study Suggests Chevy Volt Would Get 157 MPG | GM-VOLT : Chevy Volt Electric Car Site

EPA confused by Chevy Volt's fuel economy | The Car Tech blog - CNET Reviews

Test Driving a Chevy Volt - John's Journal on Autoline Detroit
...GM did not have the regenerative engines hooked up to these mules, because they’re still having issues with the calibration. If you’re driving up a long grade or traveling down the highway at 70 miles an hour and you run out of battery power the engine comes on at 4,500 rpm. So instead of tooling down the road in a whisper quiet EV, you’re suddenly assaulted by the sound of a roaring engine. The easy solution, of course, would be to bring the engine on at low rpm well before the batteries are drained. But the EPA frowns on this idea, the GM people say. If they want to get a spectacular fuel economy rating for this car, the EPA doesn’t want to see it spending a lot of its time converting gasoline into electricity. So GM is still playing around with calibration strategies and that’s why no one in the media has had a chance to drive one of these mules with the engine hooked up....
 
Moderator's note: Picking up from here: http://www.teslamotorsclub.com/off-topic/3131-viral-marketing-attempt-230-a.html
-------------------------------------

I just woke up (west coast time) and managed to just miss the live webcast. I got there just in time to see them saying "thanks for watching" and on the screen behind the presenter was 230 MPG. What total nonsense. Talk about confusing the consumer.

There's some live chat that is still going on at GM FastLane

9:10
Phil Colley: For now, some quick hits on today's announcement for those who didn't get to watch the webcast...

9:10
Phil Colley: The Chevrolet Volt extended-range electric vehicle is expected to achieve city fuel economy of at least 230 miles per gallon, based on development testing using a draft EPA federal fuel economy methodology for labeling for plug-in electric vehicles.

9:10
Phil Colley: “From the data we’ve seen, many Chevy Volt drivers may be able to be in pure electric mode on a daily basis without having to use any gas,” said GM Chief Executive Officer Fritz Henderson. “EPA labels are a yardstick for customers to compare the fuel efficiency of vehicles. So, a vehicle like the Volt that achieves a composite triple-digit fuel economy is a game-changer.”


9:12
Phil Colley:First mass-produced vehicle to claim more than 100 mpg composite fuel economy

9:13
Phil Colley: Tentative EPA methodology results show 25 kilowatt hours/100 miles electrical efficiency in city cycle

9:13
Phil Colley:

Plugging in daily is key to high-mileage performance


9:14phpvGiQcs_thumb_Volt230mpg01a.jpgpreview24.png
 
Last edited:
They wouldn't let any of my questions through on the live chat. I think mine were too logical. They only seemed to allow questions through that had some positive marketing spin (except for that last one below). Here's the web Q&A with "Chevy Volt co-creator Jon Lauckner who will help shed some light on what 230 mpg city really means."

9:19
Phil Colley: Alright everyone, I have Jon here...I'll look back through some of the questions and if you haven't sent any yet, please do. We'll get to as many as we can.
9:20
[Comment From Guest ]
Can you please explain the 230 mpg rating. I must say I balked at your gamble on EREV instead of full hybrid like toyota, but this validates your gamble.

9:22
Jon Lauckner: Yes, having a vehicle that achieves triple digit fuel economy is a game changer. The 230 mpg refers to the city fuel economy, but we also expect to have a triple digit combined fuel economy value. These preliminary numbers are based on Volt development testing with our pre-production vehicles and the draft federal fuel economy methodology developed by EPA for EREV vehicles like the Volt.
9:23
[Comment From Dean Hall ]
What is the Volt's range (city/highway) starting with a full tank and full charge?

9:23
Jon Lauckner: More than 300 miles.
9:23
[Comment From Tom ]
How long do think it will be until electric cars become as common as gas powered vehicles? 10 - 20 years or sooner?
9:28
Jon Lauckner: That depends on how the cost of batteries falls over time because pure electric vehicles, to get more than 100 miles of range, under the best conditions (low speed city driving), require very large batteries. You see, the energy density of the best batteries are orders of magnitude lower than gasoline or diesel fuel. That means, very large batteries are required to run purely electrically all the time, and that's why we think the Volt makes sense. It has enough EV range that 80 percent of drivers in the U.S. would use little or no gasoline in their daily commute, but it has the range extender to go hundreds of additional miles when recharging is not possible rather than carrying around a very large, expensive battery, which is rarely used for daily commutes.
9:30
[Comment From Ron ]
The Chevy Volt is great and make a lot of sense, but most people, myself included, are stuck with "Old" gas engine driven cars. Where do you see GM in the next few years in the realm of normal gas driven vehicles?
9:33
Jon Lauckner: In the near term, gasoline driven vehicles will still be the predominant propulsion system for cars, crossovers and trucks. So we are developing further improvements to the gasoline engine to improve its efficiency. Examples include further inprovements in valve-train technology, homogeneous charge compression ignition, downsizing and turbocharging of engines, etc. The idea is to improve the thermodynamic efficiency of internal combustion engines to the maximum possible extent, but there are limits (second law of thermodynamics) and the cost for additional efficiency is much higher as you approach the limit of engine efficiency. That's why the Volt's important because it strikes out in a bold new direction, using electricity as its primary fuel instead of petroleum.
9:34
[Comment From Mark Cullen ]
There have been discussions regarding moving the Volt technology into other products that are built on the same platform (Delta ll I believe) Are there plans to move this into trucks as well? It seems a natural idea since many pick-up trucks used by contractors, etc. are primarily used in a city application.
9:35
Jon Lauckner: Without getting specific, we obviously have looked at applying the Voltec technology to other types of vehicles, so I can confirm that, but stay tuned for future announcements.
9:35
[Comment From KEN MARTIN ]
WHY DIDNT GM COME OUT WITH THE VOLT SOONER? WHY DID THEY WAIT SOO LONG.
9:38
Jon Lauckner: While it seems like a long time ago, lithium-ion batteries, which are THE key technology, was only possible to apply in automobiles relatively recently. It was the development of li-ion batteries for automotive application that makes the Volt possible now and not five or ten years ago. In fact, when we announced the Volt, we didn't actually have a battery supplier, nor a final design for the pack (January 2007). We come a long way in a very short period of time.
9:39
[Comment From Vince Devine ]
Will GM pursue an all Electric Sports Car similar to the specs of Tesla Signature 100? Combine this with GM design and I'm in! 2010 Camaro owner and Chevy Corvette owner!
9:39
Jon Lauckner: You never say never in this business because who would have predicted some years ago that we would do the game-changing Chevy Volt, but that's not part of our planning at the moment.
9:40
Jon Lauckner: Alright, time for a couple more before Phil heads to design and I head back to meetings.
9:41
[Comment From Statik ]
The EPA rated the Volt at 25 kilowatt hours/100 miles electrical efficiency in city cycle. Does that not now mean with the Volt (which uses approximately 8 kWh of power) the AER in the city is officially 32 miles?
9:50
Jon Lauckner: Hey statik.

We are still confident that we will deliver 40 miles of autonomous electric range (AER) on both the official EPA city and highway tests, so no change there. The EPA draft methodologyreduces the laboratory result take into account a number of factors such as the use of air-conditioning, more passengers in the vehicle, cargo, etc. So, that's the difference between the "up to 40 miles" that we stated for some time (based on EPA city and highway) and the methodology used by EPA. And, nothing is final until we run an official test which won't happen for several months.
9:50
Jon Lauckner: Alright guys, thanks for all the questions, I have to run now.
 
Last edited:
GM's 230 MPG Rating Is Unrealistic

GM's 230 MPG Rating Is Unrealistic

Darryl Siry|Aug. 11, 2009, 11:15 AM

Will wonders never cease in cleantech communication?

GM announced today that the EPA has given the GM Volt a MPG rating on the city cycle of 230 miles. Sounds great, right?

The problem is that anytime you try to get to "miles per gallon" using vehicles that don't necessary use "gallons" you end up in a very strange debate with very strange outcomes.

...

So is the Chevy Volt almost twice as efficient as the Tesla Roadster? Hardly. If you apply the logic that the EPA seems to have applied in assigning the rating then the MPG of the Tesla Roadster, or any EV for that matter, would be infinite.
 
230 MPG?!? GM Jolts MPG Standard With Volt | Automakers | Financial Articles & Investing News | TheStreet.com
...Not to be outdone, and also joining the Volt on the showroom floor next year, is Nissan's electric plug-in offering. Last week the company announced the coming of its Nissan Leaf and today reiterated that the hatchback would likely get 367 miles per gallon using the same EPA framework...

----

(These inflated EPA MPG numbers are one thing. How about the MPG numbers that will be used for CAFE standards ?).
CAFE vs. EPA: Obama's MPG targets are closer than you think
...It's also important to note that the Obama Administration was talking about CAFE mpg numbers, not the EPA mpg numbers that appear on a car's window sticker. Though they start with similar mpg data, the EPA revises its mpg numbers to more closely resemble real-world driving habits, while CAFE has not changed their testing formula since 1975....
 
Last edited:

Can we now officially say the Tesla Roadster gets infinite MPG?

IMO even if they are going to use a single rating (rather than a separate range rating, depleted mode mpg rating and maybe even a kWh/100mile rating like the Roadster has) they should weigh it to fit with EVs better.

Chevy Volt gets 230 mpg, but how? — Autoblog Green
From this report from Autobloggreen's report:
http://www.nrel.gov/vehiclesandfuels/vsa/pdfs/40377.pdf

It seems a PHEV30 only gets about 90mpg using the NREL's method. This seems to fit better with the ~135mpg the Roadster gets for example. And how does this 230mpg number fit the ~256mpg number the Roadster has for it's CAFE rating?

Perhaps the Volt's mpg number will fit better after they announce the combined rating rather than only the city rating.
 
Last edited:
I asked somebody from GM today about the EPA MPG approach. I said "OK, but then by that that logic any EV would get infinite MPG?" and he/she said "Yeah."

I'm waiting to see how long before the Tesla website says "Infinite MPG", or if past is prologue, it will say "higher than infinite MPG"
 
I asked somebody from GM today about the EPA MPG approach. I said "OK, but then by that that logic any EV would get infinite MPG?" and he/she said "Yeah."

Lyle spoke with "Larry Nitz, GM’s executive director of hybrid powertrain engineering" and has a bit more info on the calculation confirming what Siry learned:
How the Volt’s 230 MPG Designation was Calculated | GM-VOLT : Chevy Volt Electric Car Site


...

What was the percentage of time or miles in EV mode that was used?

The number was calculated by the EPA using this probabilistic curve and it had the statistics of the population in it.

How about the petroleum equivalence factor (PEF), is that included?
There will be on the label itself an accounting for the gasoline equivalent of KWH used. That’s a separate conversion that will get melded in another way and is not included in the MPG estimate.


So in summary, Nitz explains that the average Volt driver charging his car nightly would can expect to burn one gallon of gas for every 230 miles traveled over time based on the behavior of a particular random population that was studied in 2001.

...
I said somewhere yesterday (I guess not here) that the appropriate response should be ridicule. There should be enough backlash that GM and EPA are embarrassed into not using this methodology.

Their marketing department maybe be able to say that if you only drive in the city, statistics show that on average you might only use one gallon of gas every 230 miles, provided you charge every night. (... err.. now how many people that live in the city currently have nightly charging available??? ... that's a separate issue.) But it should not be an official number. Sensible people want separate EV and hybrid numbers.

The other issue is how this will factor into CAFE calculations. They've admitted that the 230MPG number ignores the electric component. Is this going to allow GM to sell more vehicles with poor fuel economy?
 
Last edited: