The Volt by Chevrolet is a range extender concept, or an Extended Range Electric Vehicle.
This simply means that the onboard batteries are charged by a 4 cylinder generator set powered by gasoline.
You can also charge the car's batteries via a charging cord which will plug into a home outlet.
Chevrolet Volt Explained
This allows 40 miles of travel using the stored charge in the 16 kw/hr lithium ion batteries.
This batteries only range will be extended to 640 miles by the onboard generator.
Unlike most hybrid cars, it runs exclusively on battery electric power.
This is made possible by a 53kw generator that charges as you drive to produce 111Kw via the electric drive motor.
Now The EPA and GM have announced that the car gets an EPA rating of 230 mpg, which is fantastic..
Which means in reality, from the Volt website...
Q: How many miles per gallon will the Chevy Volt get?
A: A bit of a trick question. For the first 40 miles it will get infinite mpg, because no gas will be burned. When the generator starts, the car will get an equivalent of 50 mpg thereafter. One can calculate the average mpg per for any length drive starting with a full battery: Total MPG = 50xM/(M-40)
Q: What is the driving range of the Chevy Volt?
A: The car is being designed to drive at least 40 miles on pure electricity stored in the battery from overnight home charging. After that the gas engine will kick in and allow the car to be driven up to 400 miles on a full tank (6-7 gallons) of gas.
Q: What is the range of the Volt...
A: 40 mile range on batteries
635 mile range on gas engine
675 mile total range
50 mile per gallon on gas engine
I like to think in terms of Miles Per Gallon, so I just take number of gallons in the tank, and divide it into the range of the Volt, which gives me approx 58 to 90 mpg, more realistic, you will agree...
And a fantastic improvement on ICE cars, all because of the efficiency improvement of adding an electric motor, not to mention the performance improvement...
This is the killer feature of the Volt, as the major problem with electric only cars is that when the batteries are flat, that's it.
Most consumers don't like the idea of being "limited" to driving only a set range.
In this car, 640 miles range is far enough for most people to be impressed with it.