These teams both showed up in overweight Prii that were aerodynamically close to stock. Not even BITW's daily driven, ecomodded, Briggs & Stratton diesel Metro could compete: 51.1mpg.
It goes to show you how tough these tests are for the current generation of road vehicles to pass.
I really like Edison2's racing-bred approach of "designing to a very narrow set of specifications". The X-Prize Foundation wants to hand the prize to a drivable, ownable, marketable car, and the pressure is really on them to make sure the specifications capture that. I have my doubts about the marketability of some of the cars left in the running, but this competition has hatched a few cars I might want to own.
I think these results speak for themselves! The electric cars are in general, giving much better efficiency, and several of those (the X-Tracer, FVT, and the Aptera) also have excellent acceleration. The Li-ion, Illuminati, TW4XP, and Edison2 (among others) were not as quick -- the Li-ion and Edison2 cars are through to the finals, though. I am sad that neither the FVT eVaro nor the Illuminati Seven made it through, due to (relatively) minor technical reasons. They failed at the moment (which is how racing/competitions work, to be sure), but I think their problems are solvable, and the strong merits of their vehicles are obvious.
The Aptera is through, but still a bit disappointing -- it's aero is equal or better to anybody (save the X-Tracer), but their efficiency seems to have suffered. It barely betters the Tata, which is "just" a well executed EV conversion of a decent but ordinary hatchback. The Global-E had an ignition mapping error that made their number lower.
So the lowest MPGe of an electric drive; the AMP'd Sky was 86.7MPGe (Tango was 86.8), while the best of a car with an internal combustion is the Edison2 #97 at 101.4. (Actually, the FVT has a ICE powered generator onboard, but did not need it *at all* in the X-Prize.) The hybrids all were all below the 67MPGe -- except the WSU at 92.5 (and the FVT).
The average of the 12 vehicles using electric drive MPGe (I'm including the FVT in this) was 134.7MPGe
The average of the 6 hybrids (not including the FVT) was 61.26MPGe
The average of the 5 internal combustion drive cars was 82.92MPGe
The X-Prize results table does not include weights, but I daresay that the average weight of the internal combustion cars was lowest (the Edison2 and Spira are all much lighter!).
The best aero drag is on the X-Tracer, followed by a very close group including the Aptera, Edison2, Li-ion.
I think these results speak for themselves! The electric cars are in general, giving much better efficiency,
That's apparently true, however, electrics are given about a 3-to-1 advantage over gas cars in the MPGe formula because it's not a well-to-wheels calculation. Here's an explanation of it from this blog http://autoxprize.typepad.com/axp/20...ing-mpge.html:
I hope the X-prize team makes the correction to the MPGe calculation as soon as possible. The DOE approach is a reasonable choice, as already pointed out by others. The rationale:
1) The current calculation is fundamentally incorrect since it assumes electricity generation at 100% efficiency.
2) It does not reflect a fair comparison of technology or vehicle. Suppose you have an electric car with battery as power source. The electricity is generated by an efficient (say 35%)gas-powered generator sitting in the car. You can measure this car's mpg directly. And you can also measure the electricity generated in Kwh and calculate the MPGe. The correct calculation will give the same result.
Let put some numbers here. Suppose 1 gallon of gas generates enough electricity to run 50 miles. Direct mpg=50 mile/gallon.
1 gallon of gas =116,090 BTU. At 35% efficiency, the electricity generated would be 116,090 BTU*35%/3.412BTU/Wh =11908 Wh.
Therefore, e=11908 Wh/50 mile =238 Wh/mile
MPGe=EG/(e*EW)=116090/(238*3.412)=143 mile/gallon. Now you see the problem with this calculation. You boost the fuel efficiency by 2.87 times simply by a calculation mistake.
Posted by: Hengning Wu
and:
The plug-to-wheels (PTW) standard gives a misleading view of the energy used by competing cars, and can not provide a fair method for comparing efficiency. Is it better to burn 500 pounds of coal at the power plant to fuel your electric car, or 10 pounds of gasoline to fuel your gas-powered car?
Wait… those figures can’t be right can they? No, they are not, but the only way we can know that is by measuring from well-to-wheels. If we measure only from plug-to-wheels then we are saying it doesn’t matter whether electricity is created by burning whales or by using photovoltaic cells. We’re saying we don’t care.
About a decade ago, advocates for electric cars were calculating MPGe of 59 for the GM EV1 (http://www.radix.net/~futurev/pwrplnt.pdf). Now, the Tesla, a less efficient vehicle, is portrayed (in your chart) as being nearly twice as efficient as the EV1. (Even the relatively old tech Toyota RAV4 and Nissan Altra also get figures over 100 MPGe despite the fact that both consume more energy than the EV1.) The difference is that the Tesla is measured PTW (which does not account for the energy source) whereas the EV1 was measured well-to-wheels (WTW), which does account for the energy source. The WTW concept has long been used by environmentalists, engineers, scientists, and even enlightened automobile manufacturers interested in the full lifecycle costs of their products.
Given the goals of this competition, I think we should encourage people to think about where energy comes from. If all the cars in the competition flop in the marketplace but we at least get people to think about energy, the environment, and security, we will have accomplished something worthwhile. The PTW standard is counter to that principal, because it treats electricity and hydrogen (which are energy carriers, rather than energy sources) as simply showing up at the plug (or nozzle) with no resource, environmental, or security cost.
The MPGe concept is good (at least for the American market), but the PTW implementation, in which resource consumption is ignored, is not. If, instead, it is implemented in WTW fashion, then we can realistically look at the environmental and resource depletion costs of various vehicle approaches. Because old vehicles like the Nissan Altra and Toyota RAV4 ostensibly already get more than 100 MPGe, the PTW approach makes this competition seem largely irrelevant (we’re already over 100 MPGe) and gives support to the status quo. The PTW alternative (and similar thinking) also leads to the kind of confusion currently seen in the automotive world.
What confusion? Well, when the Automotive X Prize was first announced, claims of 100+ MPG fuel efficiency were rare (except from crackpots who think fuel needs to be treated magnetically or pre-vaporized). Now however, such claims are common. Plug-in Prius conversions have been advertised at 100 MPG, 200 MPG and 300 MPG. There’s a guy that claims to be able to get 100 MPG from a converted 5000 lb ‘59Lincoln! There’s a plug-in Saturn Vue conversion being advertised at 150 MPG. Even the Tesla is being advertised at 135 MPG equivalent, despite its being 600 lb heavier than the 23 MPG Lotus from which it was derived. Former CIA director Jim Woolsey claims that 500 MPG is possible in a mid-sized car! (NY Sun: The 500-MPG Car: : A Pipeline Dream, or Full of Hot Air?)
These high MPG and MPGe figures seem implausible, don’t they? Some are technically correct, if you read the fine print, or thoroughly quiz the promoter. For example, the 500 MPG car of Jim Woolsey’s dreams runs on e85, which is 15% gasoline and 85% ethanol. It is also a plug-in hybrid. So it is technically correct that very little gasoline is used, because the vast majority of energy gets to the car in the form of ethanol and electricity. But, while technically correct, the spin is extremely misleading. The energy required to move this midsized car down the road comes from three sources, and two of these sources do not show up in the accounting!
The proposed PTW standard is only slightly less misleading than Woolsey’s spin, because it fails to consider the energy source. Electricity and hydrogen are both energy carriers, not energy sources. This is explained in these links, one to an article aimed primarily at kids. (http://www.cecarf.org/Programs/Fuels...sCarriers.html EIA Energy Kids - Hydrogen)
If kids can understand this, then there is probably no need to dumb things down for the American public.
Favoring the WTW concept is not unique to obsessive engineering and scientific types. As the DOE says, in the Federal Register: June 12, 2000 (Volume 65, Number 113):
"When comparing gasoline vehicles with electric vehicles, it is
essential to consider the efficiency of the respective ``upstream''
processes in the two fuel cycles. A full description of the differences
in the processes is beyond the scope of this rulemaking, but the
critical difference is that a gasoline vehicle burns its fuel on-board
the vehicle, and an electric vehicle burns its fuel (the majority of
electricity in the U.S. is generated at fossil fuel burning
powerplants) off-board the vehicle. In both cases, the burning of fuels
to produce work is the least efficient step of the respective energy
cycles."
"Therefore, the PEF includes a term for expressing the relative
energy efficiency of the full energy cycles of gasoline and
electricity. This term, the gasoline-equivalent energy content of
electricity factor, abbreviated as Eg, is defined as:
Eg = gasoline-equivalent energy content of electricity =
(Tg * Tt * C) Tp
where:
Tg = U.S. average fossil-fuel electricity generation
efficiency = 0.328
Tt = U.S. average electricity transmission efficiency =
0.924
Tp = Petroleum refining and distribution efficiency = 0.830
C = Watt-hours of energy per gallon of gasoline conversion factor =
33,705 Wh/gal
Eg = (0.328 * 0.924 * 33705)/0.830 = 12,307 Wh/gal"
Using the DOE approach, the Tesla, which uses 245 Wh per mile, (based on their new claim of 220 miles per 53.9 kWh charge) would get 50 MPGe. That is an impressive doubling in efficiency over the much lighter Lotus equivalent. It also falls in line with the 59 MPGe of the more efficient EV1.
The hard work of determining upstream efficiencies has already been done, and numbers are given in the GREET charts used for the CO2 threshold calculations. If WTW makes sense for CO2 calculations, how can it not make sense for MPGe calculations? If the GREET figures are trusted for CO2 emissions, then they must be trusted for MPGe calculations.
PTW is counter to the goals of the X Prize competition. WTW supports those goals.
Posted by: Ken Fry
The Following User Says Thank You to Patrick For This Useful Post:
I think that the X-Prize competition is fulfilling the objective of focusing on vehicle efficiency. Starting with the results so far, I am hoping to contribute to the discussion and to the process.
Here's the link to the PDF that shows the results of the X-Prize Knockout Round:
The measured MPGe of the teams in this round -- remember this is the Combined number from the City, Urban, and Highway tests:
American HyPower 54.5 Hybrid
Spira 84.8 ICE (E10)
FVT eVaro 152.5 Hybrid (serial)
Zap 111.0 EV
Tata 134.3 EV
Electric Raceabout 128.1 EV
AMP 86.7 EV
West Philly (MS) 63.5 Hybrid
West Philly (Alt) 53.7 Hybrid
Global-E 50.4 Hybrid
Li-ion 182.3 EV
Aptera 140.1 EV
TW4XP 107.0 EV
WSU 92.5 Hybrid
Tango 86.8 EV
BITW 51.1 ICE (diesel)
X-Tracer (#72) 180.0 EV
X-Tracer (#79) 188.8 EV
Illuminati 119.8 EV
Enginer 53.0 Hybrid (electric/ICE w/ steam heat recovery)
Edison2 (#95 Alt) 97.0 ICE (E85)
Edison2 (#97 MS) 101.4 ICE (E85)
Edison2 (#98 MS) 80.3 ICE (E85)
I think these results speak for themselves! The electric cars are in general, giving much better efficiency, and several of those (the X-Tracer, FVT, Tata, and the Aptera) also have excellent acceleration. The Li-ion, Illuminati, TW4XP, and Edison2 (among others) were not as quick -- the Li-ion and Edison2 cars are through to the finals, though. I am sad that neither the FVT eVaro nor the Illuminati Seven made it through, due to (relatively) minor technical reasons. They failed at the moment (which is how racing/competitions work, to be sure), but I think their problems are solvable, and the strong merits of their vehicles are obvious.
The Aptera is through, but still a bit disappointing -- it's aero is equal or better to anybody (save the X-Tracer), but their efficiency seems to have suffered. It barely betters the Tata, which is "just" a well executed EV conversion of a decent but ordinary hatchback. The Global-E had an ignition mapping error that made their number lower.
So the lowest MPGe of an electric drive; the AMP'd Sky was 86.7MPGe (Tango was 86.8), while the best of a car with an internal combustion is the Edison2 #97 at 101.4. (Actually, the FVT has a ICE powered generator onboard, but did not need it *at all* in the X-Prize.) The hybrids all were all below the 67MPGe -- except the WSU at 92.5 (and the FVT).
The average of the 12 vehicles using electric drive MPGe (I'm including the FVT in this) was 134.7MPGe
The average of the 6 hybrids (not including the FVT) was 61.26MPGe
The average of the 5 internal combustion drive cars was 82.92MPGe
The X-Prize results table does not include weights, but I daresay that the average weight of the internal combustion cars was lowest (the Edison2 and Spira are all much lighter!).
The best aero drag is on the X-Tracer, followed by a very close group including the Aptera, Edison2, Li-ion.
As many have said, the X-Prize is setting a very high standard (which is both good and bad). They are essentially looking for the complete package, and virtually no glitches. Even the well financed/professional teams had several glitches. I would have set up the X-Prize a bit differently; to measure (and therefore emphasize and encourage) the four main things that need to be improved to get the maximum efficiency.
Those four critical things are; from most important to least important (as I am interpreting the Knockout results):
I would have scored these in relative terms, which pits each vehicle against the others (rather than setting standards that are somewhat arbitrary). On drivetrain efficiency, I would either use a dynamometer or the best result of the three economy tests: the City, Urban, or Highway. (This will indicate what vehicle is good for a particular role, and measures the drivetrain at it's best.)
For Drivetrain Efficiency, the points awarded would be the best MPGe x Number of Seats. So, using the Overall MPGe for 23 vehicles that competed in the Knockout Round listed above (we do not have the separate measured results from the City, Urban, and Highway test): the X-Tracer #79 would be 188.8 x 2 = 377.6 points, and so on. The best mainstream MPGe was the Illuminati Seven: 119.8 x 4 = 479.2 points.
Aerodynamic Drag would use the Weight and the Rolling Efficiency, and the results of a Coastdown test to determine the Cd of each car. I would take the inverse of the number of entrants divided by the Cd, then multiplied by the Number of Seats: So the Aptera and the Li-ion and the Edison2 alternate cars may be at the top: 23 (22, 21) / 0.15 x 2 = ~306.6 and ~293.3 and ~280 points respectively. The Edison2 mainstream cars would get 20 and 19 (or higher depending on their Cd) resulting in 20 (19) / 0.15 x 4 = 533.3 and 506.6 points respectively.
For Weight, I would take the lightest one and score it by inverting the number of Entrants x the Number of Seats – the Spira would get 23 x 2 (seats) giving it 46 points. The Edison2 alternate car would be next with 22 x 2 = 44 points. The two Edison2 mainstream cars would be 21 x 4 = 84 points and 20 x 4 = 80 points respectively; and so on. This give priority to the cars that seat more people, and it is realistic in terms of what is achievable in the real world.
Rolling Efficiency includes tires and alignment and would be prorated for weight – a slower coastdown test using a ramp would be needed. I think an inverted number of the entrants would be a fair way to award points.
Obviously, all four of the critical factors are interrelated, and they all would be reflected in the Overall MPGe number – but testing for them and awarding points (in some manner) for them separately, helps focus the designs on the most important aspects – and more importantly helps demonstrate their performance; whether or not the designs get ALL of them right and in the right balance, and if there is something that lags (or breaks) and the vehicle is DQ'd, people will still be able to judge the merits of the design.
We could quibble about how each of these was scored – I am just throwing this out there. At this moment in time, I feel that the emphasis on the safety, and meeting the letter of the rules, etc. are distracting the designers from the main point; of maximizing the efficiency. Obviously, for a finished, production, reasonably priced, appealing vehicle – ALL of these things are also critically important. These would be determined by finished vehicle, and the buying public. But, I feel that an emphasis on the overall efficiency, and the four most important factors that directly contribute to maximum efficiency, would have better served the purposes of the X-Prize.
One of the most important things I learned while I was at the X-Prize Knockout competition was: do not dismiss or ignore anybody! There is a LOT more than meets the eye with all of the entrants, and no matter the results, all the designs have strengths – and weaknesses that are all very informative.
I also was floored by the height of passion by so many people. The sight of Oliver Kuttner with tears streaming down his face; returning from the starting line of the City Test with the first of his cars about to actually get to the heart of the matter; moves me to tears, as well. And I'm quite sure that every person involved in the X-Prize, who has put in a similar Herculean effort, feels the same.
I think the source-to-wheels would swing the equation even more to the EV's advantage! The amount of energy "invested" in refining gasoline ALONE is enough to power the EV's; let alone the gasoline itself.
Please watch the "Fully Charged" pilot video podcast:
I don't believe that the numbers represent the true MPG of the vehicles. Some of them had low numbers because they had stuff that was disconnected and were not allowed to do any repairs. I also know that any of the mileage techniques employed on this website would not be allowed in the in the competition.
I know that George Voll (BITW) was definitely not doing his best ecodriving on the first day (City and Urban) tests. He was coming really hot (fast!) and even locked up his brakes on one stop. He did not seem to be downshifting or even coasting -- they wanted you to "linearly" slow down and he was most definitely not linear. He was sometimes coming in right behind other cars and so he had to stop for their stop, and then again for his own 5 second stop -- not good for his mileage...
I think that the X-Prize competition is fulfilling the objective of focusing on vehicle efficiency. – I am just throwing this out there.
I tend to agree with you, except that the way the competition is scored is biased toward electric vehicles. They may be dominant in the marketplace, someday, but the interim solution is probably going to be a petrol-powered vehicle that gets great mileage. I believe a lot of teams (Edison2 excepted) looked at the rules and decided that there was no way to win with gas, so they didn't bother entering. How much innovation was left untapped? We'll never know. Notice that not one major manufacturer entered the Demonstration class. Why not? My guess is: too much hassle, not enough payoff, and again the bias toward electrics. Don't get me wrong, I'm not against electrics - I used to own one - but I think the playing field should be level.
To show an electric that gets 150 MPGe compared to a gas car or hybrid that gets 50 MPG is disingenuous, IMO, because the actual well-to-wheels totals for both cars is about 50 mpg, especially considering the limitations that electrics currently have.
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