BS METER PEGGED! Even an ultra-efficient capacitor with a huge storage capacity is going to require an amount of power (over time) from the "Grid" which will equal the usage of the car's electric motor(s)! A kilowatt (1000 watts) of power equals about 1.34 HORSEPOWER!
Assuming 100% efficiency (impossible), a mere 10HP electric motor running for ONE HOUR consumes about 7.46 KWH! A "5 minute charge" at the home would equate to approximately an 89.5 KW power drain at the home! Not impossible in and of itself but, a MAJOR refit of home feedlines would be required and the cables would be monsterous in size (not to mention the heat and current degradation!
I am certain that more technically proficient Freepers can come up with more exact figures but..., other than a super golf cart, I don't see it. Now, an OVERNIGHT charge at a more moderate power drain, stored by an ultra-efficient, light weight capacitor bank DOES hold great promise for moderate range lighter weight commuter automobiles!
I could see something like this being viable in a hybrid vehicle, where you could get along with a much smaller gas engine operating closer to peak more of the time, with the ultracap powering an electric motor to give the car peppier acceleration.