PG&E just went to $0.36/kWh which works out to $0.09/mile. The Prius prime gets 55mpg. If gas drops to $5/gallon, hard to find in the Bay Area, it's a wash. If it drops to $4.50/gallon it's cheaper to use the gas engine. I know people with EV's where they pay $0,05/kWh, but not around here.