Well electricity is a lot cheaper than gasoline, so in a car like the Chevy Volt or Nissan Leaf, the price premium for the battery can pay for itself over time (although it will take longer now due to the drop in gas prices... but those are probably temporary).
With a Volt you also have that gas engine & tank built in so that it turns into a regular gas car after the battery is depleted.
Well, I'm not at all enamored with the idea of a battery powered car, but I do like the electric drivetrain.
My proposal is to lose the battery pack and replace it with big capacitors and a small but capable powerplant to keep them charged, or to be able to directly power the motors for continuous high speed or multiple bursts of acceleration (hence the turbo). The capacitors can charge very quickly.
The desired result would be a unit with Tesla-like performance, and a car that would never need a battery pack, nor run out of juice-AND-get respectable fuel mileage. Not to mention last a good long while.