3 ms·

These numbers are meaningless; the EPA had to make up some kind of methodology for assigning a "mpg" number to a car which isn't actually burning any gasoline a

by hugh3 16y ago

These numbers are meaningless; the EPA had to make up some kind of methodology for assigning a "mpg" number to a car which isn't actually burning any gasoline at all. In my opinion it should say "Infinity miles per gallon" on the electric side of the label. I'm guessing that half the reason they don't is because they have these CAFE "average MPG standards" which they want to force automakers to adhere to, and throwing infinities into the averages tend to mess things up. I don't know why people are so down on the Volt -- I think it's an excellent piece of technology, and probably the way of the future. An electric car with a petrol-powered generator to keep you going after the batteries are flat is the best of both worlds -- you can burn zero fuel most days, but still drive a thousand miles in a day if you feel like it.

tshtf 16y ago
I'm not sure "infinity miles per gallon" makes sense on the electric side. The EIA publishes statistics about power generation in the United States: http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html Since 68.8% of power generation in the United States comes from non-renewable resources (coal, gas, and petroleum), it makes sense that the EPA would use some sort of system to describe the MPG for cars running on electric power.
- pyre 16y ago
  Then why aren't all of the energy costs associated getting that gasoline to the pump factored into the cost of MPG on normal cars then? People are so quick to point out the 'hidden costs' of electric cars, while ignoring things like: * Drilling for crude oil * Harvesting crude oil * Shipping crude oil * Refining oil into gasoline * Shipping gasoline ... etc ...
- hugh3 16y ago
  They really should give it in miles-per-megajoule or something, though, rather than "mpg equivalent", which only serves to confuse people. What is a "gallon equivalent" of electricity anyway? Is it the amount of electricity you'd get if you burned the gallon and generated electricity at 100% efficiency? Or the amount that you'd get if you used it to generate electricity with power-plant efficiency (which incidentally is pretty high)? Or perhaps it's the amount of electricity you get if you burn the CO2-emissions equivalent amount of coal? Or the dollar equivalent amount of coal? Or... well, there's a bunch of other possible definitions.
- wtallis 16y ago
  Miles per gallon of coal? If you're going to try to come up with an equivalent number, are you going to base it on carbon emissions or on cost to the consumer? Either way, it will be highly variable: gas prices fluctuate relative to electricity prices, and different sources of electricity lead to different emissions per kWh. At least with gasoline-powered cars, the differences between EPA estimates and real-world consumption are factors under the driver's control. This isn't the case with BS numbers for EVs, so the numbers end up being pretty much useless to the consumer. If the number is not going to be useful to the consumer, then there's no reason to mandate it be on the sticker.
  - hugh3 16y ago
    If the number is not going to be useful to the consumer, then there's no reason to mandate it be on the sticker. Having some sort of number there is useful; as electric cars become more common we'll need some way of comparing their efficiency. Right now you can find out that the Volt at 93 "mpge" is slightly less efficient than the Nissan Leaf at 99 "mpge". I'd still much rather have it in the less ambiguous units of miles per kilowatt hour. (Or if they really want to appeal to physicists, they should give it in units of inverse force. 1 mile per kilowatt hour = 447.04 inverse MegaNewtons.)
ck2 16y ago
Their chart is super confusing too, unless you stop and really study it and read the fine print. Basically the most useful part on that chart is the lower right where it's 50% more cost effective per mile under 45 miles. Maybe this is a "first gen" problem and they can get it to three, eventually four times as cost effective in a few years. I bet Japan or Germany will figure it out first.
- hugh3 16y ago
  Three or four times as cost effective? Not unless someone starts selling electricity for cheaper. This is just rubbing up against the laws of physics. If you wanna move a one-point-something ton hunk of metal around it takes a certain amount of energy. All the components are operating at reasonably high efficiency, so you're not going to get a threefold increase in efficiency by any clever tricks.
  - ck2 16y ago
    Reducing car weight and profile will help too, we can't keep driving these huge cars (though it doesn't have to be super small either). My electric bike can go nearly 40 miles @ 25mph on a 48v 20ah battery. The difference is weight and wind profile.

by hugh3 16y ago

tshtf 16y ago

I'm not sure "infinity miles per gallon" makes sense on the electric side. The EIA publishes statistics about power generation in the United States: http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html Since 68.8% of power generation in the United States comes from non-renewable resources (coal, gas, and petroleum), it makes sense that the EPA would use some sort of system to describe the MPG for cars running on electric power.

pyre 16y ago
Then why aren't all of the energy costs associated getting that gasoline to the pump factored into the cost of MPG on normal cars then? People are so quick to point out the 'hidden costs' of electric cars, while ignoring things like: * Drilling for crude oil * Harvesting crude oil * Shipping crude oil * Refining oil into gasoline * Shipping gasoline ... etc ...
hugh3 16y ago
They really should give it in miles-per-megajoule or something, though, rather than "mpg equivalent", which only serves to confuse people. What is a "gallon equivalent" of electricity anyway? Is it the amount of electricity you'd get if you burned the gallon and generated electricity at 100% efficiency? Or the amount that you'd get if you used it to generate electricity with power-plant efficiency (which incidentally is pretty high)? Or perhaps it's the amount of electricity you get if you burn the CO2-emissions equivalent amount of coal? Or the dollar equivalent amount of coal? Or... well, there's a bunch of other possible definitions.
wtallis 16y ago
Miles per gallon of coal? If you're going to try to come up with an equivalent number, are you going to base it on carbon emissions or on cost to the consumer? Either way, it will be highly variable: gas prices fluctuate relative to electricity prices, and different sources of electricity lead to different emissions per kWh. At least with gasoline-powered cars, the differences between EPA estimates and real-world consumption are factors under the driver's control. This isn't the case with BS numbers for EVs, so the numbers end up being pretty much useless to the consumer. If the number is not going to be useful to the consumer, then there's no reason to mandate it be on the sticker.
- hugh3 16y ago
  If the number is not going to be useful to the consumer, then there's no reason to mandate it be on the sticker. Having some sort of number there is useful; as electric cars become more common we'll need some way of comparing their efficiency. Right now you can find out that the Volt at 93 "mpge" is slightly less efficient than the Nissan Leaf at 99 "mpge". I'd still much rather have it in the less ambiguous units of miles per kilowatt hour. (Or if they really want to appeal to physicists, they should give it in units of inverse force. 1 mile per kilowatt hour = 447.04 inverse MegaNewtons.)

ck2 16y ago

Their chart is super confusing too, unless you stop and really study it and read the fine print. Basically the most useful part on that chart is the lower right where it's 50% more cost effective per mile under 45 miles. Maybe this is a "first gen" problem and they can get it to three, eventually four times as cost effective in a few years. I bet Japan or Germany will figure it out first.

hugh3 16y ago
Three or four times as cost effective? Not unless someone starts selling electricity for cheaper. This is just rubbing up against the laws of physics. If you wanna move a one-point-something ton hunk of metal around it takes a certain amount of energy. All the components are operating at reasonably high efficiency, so you're not going to get a threefold increase in efficiency by any clever tricks.
- ck2 16y ago
  Reducing car weight and profile will help too, we can't keep driving these huge cars (though it doesn't have to be super small either). My electric bike can go nearly 40 miles @ 25mph on a 48v 20ah battery. The difference is weight and wind profile.