The Numbers Don't Lie
Wednesday, October 12, 2011 at 10:44PMOur prototype electric Very Light Car (eVLC) was recently in an EPA-accredited lab for the full gamut of certified economy and range tests. Often this kind of thing is shrouded in secrecy but we thought it might be interesting to publish and discuss the actual results sheet (click here for a pdf).
Starting in the top left corner, we have Roush Industries’ logo. Jack Roush is well known as a successful NASCAR team owner and at the time of writing one of his drivers, Carl Edwards, is leading the Sprint Cup series standings. Less well known is that Roush has facilities all over the Detroit area providing engineering and testing services for the auto industry. We have enjoyed working with the professionals at their emissions lab in Livonia, MI.
The first block of data under the logo names the car tested, in this case VLC chassis #004, and, because it’s critical to the validity of the results, the tire pressure used. 44 psi is Continental’s recommended pressure for the DOT approved tires we use on the VLC.
The next block of information is the dyno settings. Because of its battery, the eVLC is heavier than our E85 powered cars, weighing 1140 pounds and, since the EPA standard is to add 200lb for the driver, Roush set the dyno for 1340 pounds. The car’s drag and rolling resistance characteristics are defined by 3 numbers determined by an SAE standard coastdown test. We’ve written extensively about this before and our numbers are A=6.31, B=0.1862 and C=0.00433. There’s a procedure to match the dyno to the coastdown ABC numbers and the compensating numbers are on the right. Once they’re set, the dyno provides exactly the same resistance to motion and acceleration as the real car on a straight and level road on a windless day.
Is “straight and level on a windless day” the same as “real world”? While you don’t have to deal with wind and corners in the lab, straight and level does prevent people measuring energy consumption coming down the mountain and ignoring what it would take to go back up. In any event it is the EPA standard and what everyone adheres to.
The CARB All Electric Urban Range test consists of running successive EPA Urban Dynamometer Driving Schedules (UDDS) with a 10-minute soak after each completed cycle. This continues until the car can no longer maintain the required speed trace or until the test is called off. The UDDS cycle, which can be found in 40 CFR, Part 86, Appendix I, is shown below.
Edison2’s Ron Cerven drove the test. Although Roush didn’t record the car’s odometer reading, that is not significant because the dyno has a very accurate odometer built in, and it shows that we went 114.781 miles on a charge.
A word about driving the test. The speed profile from the graphic above is presented as a rolling strip chart and the driver has to keep the car’s speed on the target line. There’s a permitted error band but it’s tight and you have to concentrate hard to stay in the acceptable range. If you go outside the error band for more than a few seconds, in a test lasting several hours, you fail. Our being issued a results sheet shows Ron drove the test within the specs.
Charging the battery must begin within 1 hour of the range test finish and the electricity used is measured and recorded. There’s a brutally simple way of making sure this is an honest full charge: you have to do the Highway range test the following day on the electricity you put in.
Roush measured 11.0 kWh of electricity, and the EPA says 1 gallon of gas is 33.705 kWh, so the Equivalent Fuel Economy is 114.781 * (33.705/11.0) = 351.7 mpg.
Note the DC energy used figure of 8.5 kWh. This is measured at the car’s electric motor and the 22.7% reduction is due to losses in the charger, the battery and the controller. If you were to cherry pick and use 8.5 kWh in the calculations, the miles per energy gallon would be higher but the EPA very properly insists the number of record is what goes into the charger.
The same test procedure is used on the highway range test, using the EPA’s Highway Fuel Economy Test (HWFET) cycle. This is run repeatedly with a 10 minute soak between each pass until the vehicle can no longer maintain the drive schedule or the test is called off. Once again, battery recharging must start within an hour of the test’s completion. The electricity used to recharge is measured and recorded. The eVLC went 113.331 miles on 11.0 kWh for 347.3 mpg equivalent fuel economy.
EPA procedure is to determine range by averaging Urban and Highway mileage, weighted 55% Urban, 45% Highway and rounded to the nearest 10. Our 114.1 mile combined range therefore got rounded down to the 110 mile official number for Calculated Driving Range.
Further down on the sheet, the last two rows on the sheet involve the EPA’s recently introduced 5-cycle standard. Time was, a new car’s “sticker” mileage was determined solely by the 55/45 combination of the UDDS Urban and HWFET Highway cycles. Since 2008 has been determined by calculated values according to EPA formulae which factor in cold weather (meaning the heater’s on), hot weather (meaning lots of a/c use) and aggressive driving.
At the bottom is the number that really matters: MPG with 30% Cap (Combined) of 244.8 is the eVLC’s “sticker” energy mileage according to the current EPA methodology. It directly compares with the Leaf’s official 99 mpg and the Volt’s 93 when running on its battery. To restate this in different words, Edison2’s eVLC scores 245% and 261% of Nissan’s and Chevy’s energy mileage.
The EPA also applies their 5 cycle formulae to determine the official value for range. In our case, they calculate 79.9 miles. The corresponding Leaf number is 72.5 miles on a battery almost 2 ½ times the size.
Lastly, although the X PRIZE wound up more than a year ago, we thought it would be interesting to see what we would have scored with an electric VLC so we ran the X PRIZE test which consists of 4 successive UDDS + HWFET drive cycles with a 10 minute gap between each one. The whole test was a touch over 71 miles and we used 7.0 kWh of electricity to do it. That electricity is equivalent to 0.208 gallons of gasoline so, the way the X Prize would measure it, we did 71/0.208 = 341.8 MPGe.
341.8 MPGe is an interesting number because we’ve demonstrated 104 MPGe in the same tests with our E85 ethanol/gasoline blend powered cars. When the cars are very similar and the tests are the same, why the factor of 3+ difference? The answer is the motor of an electric car is greatly more efficient than even the best combustion engine. Against that, the electricity measurement is plug-to-wheels and ignores the upstream inefficiencies (generation and transmission losses) of the electricity supply chain.
Regardless, at Edison2 we’re energy source agnostic. Our efficiency is in the car, and whatever you run the car on, you just don’t need as much of it.
Reader Comments (14)
Please please work on a kit ASAP. I'll keep my '94 escort that gets 48 mpg with hypermiling going for three or four more years, but this is the future. Great work!
Re: Crash Testing
Deer kill a lot of people each year in vehicle collisions. They are thick on my commute. Please consider a deer collision when you test and in your design. At present it looks like a deer would flop right into the windshield area, and I don't know how strong that is. Thx.
I’m glad to see that Edison2 continues to hammer away again and again with the value of low mass and clean aerodynamic design. Some one must do this. Having won the X prize you are in a position to speak with some authority. While the electric version has some significant advantages over it’s E85 predecessor, additional numbers must be included for a more complete assessment e.g. the ease and cost of producing the two power plants at various scales of production. Would you be able to share any numbers?
Great write-up guys! The FACTS are going to sell this one.
Are you using the Agni motor and Thunder Sky batteries?
Hi guys!
I second what Randal Son said... Please introduce a kit car! :)
Keep up the great work!
Excellent post -- it is refreshing to see all the specifics. And congratulations on the excellent performance!
I've got to say that not only does electricity have "overhead" energy inputs -- so does gasoline and ethanol. They don't appear out of thin air, right? These days as we are working harder to find oil, and the quality of the crude is more and more often lower quality, this overhead energy is even more than it used to be.
A recent post over at AutoBlog Green talks about the fact that the best (conservative) estimates are that it takes about 8kWh of electricity to produce each gallon of gasoline, and that leaves out the exploration, transportation -- and also the large amount of natural gas that is also used all during the extraction and refinement and transportation of gasoline and diesel. The natural gas itself then has additional overhead energy -- so suffice it to say that each gallon of gasoline represents a lot more energy than it "contains".
Here's the article on ABG: http://green.autoblog.com/2011/10/14/how-gas-cars-use-more-electricity-to-go-100-miles-than-evs-do/
Alcohol from corn has it own very long and complicated chain of overhead energy inputs; including natural gas to produce the fertilizer (corn is the SUV of plants!) and the diesel for the tractor, the trucks to take it to the refinery, and the refining process itself requires a lot of energy inputs.
So, the gallon of E85 that the VLC would have burned represents almost as much electricity *alone* as the VLCe used to travel 110 miles. And then you have to count the natural gas also used to produce the E85; along with the carbon actually contained in the liquid fuel.
The best thing about electricity is that it *can* be produced from renewable sources. Put some solar panels on your roof (you can lease your roof to some companies, and they install them for free) and you will be powering your car without any oil. Oh, and electric drivetrains require almost no maintenance, no oil changes, etc., which is yet another overhead of an ICE, that is often not considered.
So, I applaud all your efforts and congratulations on your continued successes.
Sincerely, Neil
thats good to know cause I didnt know that the battery needed to be charged within the first hour, sweet thanks :)
Any chances we'll this care in either it's electric form or with the internal combustion engine ? I like the idea very much and I was thinking how much I'd love to drive such a car.
Also very important is for it to be as cheap as possible. Having something simple and light but more expensive than the usual cars is not that good.
I really love the transparency that Edison2 gives! I'm rooting for your success.
However, I have a quibble that you are being disengenuous on the BLOG when you say the 3:1 difference between MPGe and MPG (EV vs. fuel) versions of the Edison2 car results from the higher efficiency of the electric motor. I know that you guys know different...
The truth is that there is an approx. 3:1 ratio of electric power generation vs. fuel burned at the power plant, since the average Coal power plant is ~33% efficient. This issue is, at its core, the basis of the EPA's fraudulent MPGe calculations for EV's. In other words, 1 KWh of electricity took about 3 times that much fuel energy to be created. Even if electric motors were 100% efficient, this fact remains true.
The EPA should use 34 x 2.5 = 85KWh for the equivalent of the gallon of gas, not 34 KWh. That would make a Nissan Leaf's MPGe = 99/2.5 = 40 MPGe.
Kevin,
Do you think that gasoline appears out of thin air? Because it actually takes more electricity to drive a gasoline powered car a given distance than it does to drive an electric car the same distance. So the "long tailpipe" argument also applies to gasoline cars, and diesel cars, too. The lifetime costs of driving an EV is a tiny fraction of an ICE powered car. The difference for say 40-50 years of driving is well north of $200,000.
An electric car is 2-3X times more efficient for energy put into the car per mile traveled. It just is; all else being equal. And there are important factors that allow an electric car to be even more efficient than an ICE power car:
* Much lower cooling is required for an EV, and therefore the ~10% of the overall aero drag that comes from the cooling system can be reduced to nothing or almost nothing.
* No idling and no warm up are needed for an EV, so short drives and/or in cold weather have very little affect on the efficiency. Also free wheel coasting in an EV is much easier and no idling during the coast is good for another ~10% gain. And with inherently better aerodynamics, coasting is even more efficient in an EV.
* Regenerative braking is possible in an EV, and this means that some of the kinetic energy of the moving car can be regained back into the battery; instead of heating the brakes. This also reduces brake wear, and this reduces costs and energy needed to make new brake pads, too.
* An EV has almost no regular maintenance. Because the oil and the filter and the cooling system, etc. all take energy to make and these are about 25% of the costs of operating an ICE powered car. And this overhead energy must be taken into account for the overall costs. EV's have no clutch, and no multi-gear transmission either, and some are direct drive, so there is not even transmission oil to change.
** And with an EV it is possible to put solar panels on your roof (for almost nothing down for systems from some installers) and produce the electricity you need to power an EV. So, you can completely offset ALL of your electricity use for your home and for driving your EV. This is not possible for an ICE powered car; unless you are producing your own biodiesel, and then you would also need solar PV to have a renewable energy source to produce what you need.
Neil
Neil,
I can appreciate your zeal to see us get off of fossil fuels - I actually share that desire.
However, my friend, you need to do a lot more study before you understand the true picture, instead of spewing incorrect technobabble. The big problem is that EV's do almost NOTHING to get us off of fossil fuels! They absolutely do NOT reduce total energy usage and make only a small difference in fossil fuel usage....and they put a large burden on the power grid and have huge user convenience trade-offs and costs.
See where your electricity comes from: https://flowcharts.llnl.gov/
You'll see that 70% of the USA grid is fed by burning fossil fuels. This won't be changing anytime soon.
Now, see how inefficient fossil fuel power plants are: http://cleantechnica.com/2008/06/26/electricity-generation-efficiency-its-not-about-the-technology/ and http://www.epa.gov/chp/basic/efficiency.html
You'll see that the average USA fossil fuel (Coal or Natural Gas) power plant is only 33% to <40% efficient at converting fuel energy to electricity.
There is also a 7% avg. distribution loss over power lines, and of course ~20+% loss in the EV for battery charge / discharge loss. It's true that electric motors can be >90% efficient, but that is nearly irrelevant due to all these other losses.
Note that a Toyota Prius is just as efficient: http://green.autoblog.com/2011/04/24/toyota-targets-45-thermal-efficiency-for-engines-in-next-gen-hy/
Here's a summary of the EPA's fraudulent MPGe calculations:
http://www.forbes.com/sites/warrenmeyer/2010/11/24/the-epas-electric-vehicle-mileage-fraud/
Even the TRULY WONDERFUL Edison2 EV car's 350 MPGe is "only" 100 - 140 MPG if calculated honestly. I'm not detracting from Edison2 - because their efficiency helps no matter what you power the car from!
So...if not EV's, what is the solution that eliminates fossil fuels ? There are only a few answers:
1. Work to get the power grid fed by renewable sources instead of fossil fuels. AFTER that happens, EV's might make sense. Call me back in 50 years and let's see how that's going, then we'll see if EV's make more sense then.
2. Work to replace gasoline with a renewable fuel. This could be a biofuel, or direct solar-synthesized fuel (as Sandia Labs is experimenting with), or maybe hydrogen. This would be much more direct and more quickly implementable and would leverage today's infastructure and not require huge customer convenience trade-offs.
By the way - another myth that needs to be dispelled: While it is indeed a good thing to add solar panels to your house, the fact is that about the same amount of GOOD is done whether or not you use the panels to charge an EV or to feed the grid. I have a friend that paid $30K for panels that put out enough KWh to negate his Chevy VOLT's battery charging. That's great...but $30K (plus the ~$15K cost premium of the VOLT vs. CRUZE) would have paid for a lot of gas, and by just having the panels he would negate nearly the same amount of carbon generation ....at the power plant.
Kevin,
You seem to have missed the main point of my previous post. You are adding in the previous steps for electricity, and ignoring the previous steps for gasoline.
If you add in the carbon overhead for electricity, then you must add it into the gasoline, as well. It takes a lot of electricity and natural gas and water in some cases -- to get oil from the ground, and to transport it and to refine it and to transport it again. Look at the gm/mile of carbon that the EU and the UK rate their cars. That doesn't even include the overhead to make the gasoline -- just the gasoline itself, and so EV's are far lower carbon output even with coal generation plants. 100% coal generated electricity is about equivalent to an 80MPG gasoline car *without* the overhead for the gasoline.
As I said, the "long tailpipe argument you are making is moot -- since it takes more electricity to run a gasoline car than an EV.
Driving a Nissan Leaf 100,000 miles saves you about $17,000 compared to a typical ~22MPG car -- that is fuel and regular maintenance costs.
An EV allows us to get COMPLETELY OFF of fossil fuel. You can get $0 down PV systems installed now (in many states) and having these lowers the cost of electricity you are now paying for your house -- so you are driving for "free" and using zero fossil fuels.
Sincerely, Neil
Great work done, this is a great analysis. which type of batteries you have used