In Connecticut it is only now cheaper to use electric instead of gas in my prius prime. I get 50-53 mpg highway, even over very long distances I drive to family in STL a few times a years, and electric is $0.33/kWh. So even at around 4 miles/kWh I'm paying $0.0825/mile for electric which breaks even right around $4.25/gallon. So it's really going to depend upon where you live.

That's not to say I wouldn't buy an electric car tomorrow if I had the option. My somewhat frequent long drives make gas slightly preferable but these days I'd much prefer electric.