And when the Hybrid SUVs come out, with 50-70 or more MPG then you're really getting somewhere.

Well, as long as we're defying the laws of physics let's just power it with an electrostatic anti-gravity diffusion polarization matricizer with inverse capacitance bias modulation rectification and not use any fuel at all!

A six-foot tall, 4WD, 5500 lb, off-road capable vehicle (which would be a pretty average description of a truck wearing the appellation of "SUV") carrying enough engine and battery capacity to give acceptable acceleration is not likely to deliver "50-70 or more MPG".

[tongue-in-cheek]
Hey, I've got it! We equip all the gasoline pumps with a bit of electronics on the fill nozzle that will read the current odometer mileage of the vehicle and what the mileage was the last time the vehicle was refueled, thus determining the miles traveled. The pump will then dispense only as much fuel as the vehicle consumed if it got 25 miles per gallon. Those with more fuel efficient cars would be able to collect fuel "credits" which they could then sell privately (at whatever outrageous price the traffic would bear) to SUV owners.
[/tongue-in-cheek]

tanstaafl.