Is GM's Volt MPG missleading?

Advertising not completely forthcoming. Film at 11!!

Seriously, though, anyone who takes marketing at face value is begging to be lied to. It’s no different than a credit card offering 0% interest, with the fine print showing that’s for 3 months, at which point it raises to 25% interest. Or a bottle of “fruit juice, made with real juice!” with the fine print saying “10% juice extract”.

In this case, GM is simply marketing the aspects of the car that are most appealing. It’s not an outright lie, it’s just not a complete disclosure. They know people are mostly concerned with the price of gasoline, and are not thinking about the cost of electricity to power the car. Therefore, they only talk about the gasoline efficiency.

@MrItty
I would like to add it seems like a very good car and I hoe for the best for GM.
I think it’s misleading because I could build a entirely electric based car and say it’s infinitely miles to the gallon. (I couldn’t actually build a electric car)

In their defense, they are using the EPA standards for how to report mileage. That they gamed the car design to up the mileage reporting is more a problem with the EPA’s standard than with GM’s advertising.

@bpeoples
Ok, I have seen them use MPG for the Volt but maybe that’s changing.

That number takes into account only the gas consumed when the batteries are low. The volt will go around 40 miles/65 km on a charge. It burns gasoline after that, to power a generator that replenishes the batteries. If you don’t drive more than 40 miles in a day, you could go for months without using any gasoline, provided you remember to plug it in at night. If you go on extended trips, I think it ends up getting around 50 MPG, which is similar to the Prius.

Now – the energy used to recharge the batteries when it’s plugged into the wall has to come from somewhere. Here in Chicagoland, about half of our electricity comes from splitting atoms. The rest comes from burning coal → CO2. “FOUL,” someone cries? Well, maybe just a little. Here’s the thing; when you burn gasoline in a car, most of the energy is wasted. The majority is waste heat. A lot of it also goes into overcoming the mechanical inefficiencies of the engine and transmission. Electric motors are far more efficient at using the power available to them, which is the reason the Prius gets such good mileage. So even though the Volt has a carbon footprint that’s larger than its MPG rating would indicate, it’s still small by comparison. Coal-fired electric plants burn carbon, but they recover more of the energy available from combustion than gas engines do. So the carbon you burn by virtue of recharging your Volt’s batteries is still less than what you would burn in a conventional car.

Here’s the math:

40 miles on a charge, then 50mpg after that. To find out how they came to the 230mpg, we have this:

230miles/gallon = (40 + x) miles / (x/50) gallons

This gives us x = 9, so you get 230 miles per gallon on a 49 mile drive. This (I assume) follows the EPA guidelines for how to test hybrid vehicles for mpg in city driving, otherwise they’d be sticking their necks out to be chopped off by a lawsuit.

But here’s the kicker:

miles 0–40 used no gasoline (see @IchtheosaurusRex for the tradeoff), miles 40–90 used a gallon of gas—that’s 90 miles to the gallon, if we just ignore reality. Miles 90–140 used another gallon of gas (now we’re down to 70 mpg)

At 240 miles, you cross the 60mpg line.

Here’s a graph:
http://bit.ly/7HcgZ