I have a plug in hybrid. It can drive about 25 miles on electric then switches over to gas. 8.8 kWh @ $0.30/kWh amounts to around $0.10 per mile. Gas here is ar

I have a plug in hybrid. It can drive about 25 miles on electric then switches over to gas. 8.8 kWh @ $0.30/kWh amounts to around $0.10 per mile. Gas here is around $0.09/mile @ 52 mpg. So, if electricity > approximately $0.30/kWh, then driving on electricity is more expensive. But if less than that electricity is cheaper. Also most gas cars don't get 50mpg, since mostly only a hybrid can really get that. So if you look at 25mpg, it ends up more like $0.60/kWh as the break even point.