And how fast do they go up a hill?
Check this out:

The Environmental Protection Agency’s website that offers car buying tips lists the best and worst vehicles based on fuel economy. Small electric vehicles top the most efficient list, while luxury vehicles are listed as top the least efficient.

Nine of the top 10 cars are electric vehicles. The 2014 Smart Fortwo electric drive convertible and coupe, which have only two seats, tops the list with 107 mpg.

Also on the list are the Fiat 500e, Chevrolet Spark, Ford Focus Electric, Nissan Leaf, Honda Fit and Toyota Prius (the only hybrid).