John,

You don't need new technology. It's already there. Ordinary cars (not the expensive hybrid technology) that run 50+ mpg can be bought as we speak. As a matter of facts, I have one, a second hand. The model has been on the market since 1997.

VW has introduced the Lupo 3L years ago. It runs 3 liters of diesel on 100 km. That's 75 mpg.

It's already there. No need for inventions. No need for break throughs. And it is much cheaper than a 15 mpg SUV. The average costs of cars like this are well below 10.000 US$.

And if you are American and want something a bit bigger:

http://www.whatcar.co.uk/car-review-pictures.aspx?RT=56&U=1

I get 45mpg (Urban commute) to 60mpg (Motorway) from this diesel, which has a larger cargo capacity than a lot of SUVs, as well as vastly better cornering. Modern diesel technology is something that might actually make a difference in the US - it's the reason why many European countries have seen flat or even slightly dropping oil usage in the past decade, despite increasing populations and passenger miles.