## 230 MPG

Tuesday, August 11th, 2009

GM’s new Volt should get 230 MPG in city driving:

The Volt is powered by an electric motor and a battery pack with a 40-mile range. After that, a small internal combustion engine kicks in to generate electricity for a total range of 300 miles. The battery pack can be recharged from a standard home outlet.

GM came up with the 230-mile figure in early tests using draft guidelines from the U.S. Environmental Protection Agency for calculating the mileage of extended range electric vehicles, said Tony Posawatz, GM’s vehicle line director for the Volt.

If the figure is confirmed by the EPA, which does the tests for the mileage posted on new car door stickers, the Volt would be the first car to exceed triple-digit gas mileage, Posawatz said.

The downside? The car will cost close to \$40,000. How much will gas have to cost for a Volt to make sense? A lot.

First, realize that the familiar miles-per-gallon metric is upside-down. What you want to know is gallons per mile — or gallons per 100 miles. If you travel 10,000 miles per year in a 10-mpg clunker, you use 1,000 gallons of gas per year. At \$4 per gallon, that’s \$4,000 per year on gas.

If you upgrade to a decent 20-mpg car, you’ll use 500 gallons of gas per year — saving yourself \$2,000 per year.

If you upgrade a 20-mpg car to a super-efficient 50-mpg car, you’ll use just 200 gallons of gas per year — which may be impressive, but it only saves you an additional \$1,200 per year.

In fact, upgrading a 20-mpg car to a 230-mpg Volt cuts annual gas consumption from 500 gallons to 43.5 gallons — which, again, seems impressive, but it only saves \$1,826 per year.

Even a pure electric vehicle using no gas — getting infinite miles per gallon — could only save you \$4,000 per year; you can’t spend less than zero on gas.

Miles per Gallon Gallons per 100 Miles Gallons per Year (10,000 Miles) Dollars Saved per Year (@\$4 per Gallon)
10 10 1000 \$0
20 5 500 2000
50 2 200 3200
230 0.43 43 3826
Infinite 0 0 4000

That said, I love the technology under the Volt’s hood. It isn’t a Prius-style hybrid; it’s an electric vehicle with a gas generator for extended range. That means no transmission.

They’d probably have a more sensible vehicle if they halved the size of the battery pack. That would dramatically reduce the cost of the vehicle, it would significantly reduce the weight of vehicle, and it would only ever-so-slightly increase the gas consumption of the vehicle.