Greener Cars for a Greener America

Yesterday, I was watching Top Gear with my dad on BBC. They had just reviewed a car (specifically a Ford F-150 V6, for all the car lovers out there like me) with a diesel engine! Most people have no idea how amazing a diesel motor is. It basically gives any car ten more miles to the gallon and is much cleaner to drive then the standard gas motors. That doesn't seem like much, but if you compare a normal pick-up with about 17 miles to the gallon to one that has a diesel and receives 27 miles to the gallon, that is a significant savings. Currently, the only "clean" diesel car that is imported into the U.S. is the Audi Q7 TDI. My father plans on buying one in the future, considering he would save about $3,000 a year in gas. These types of cars are all over Europe, so why aren't they imported?
Supposedly, Obama is for a greener America. We would be so much better off if we cut down on how much oil we consume (considering we use the most out of any other country). So why not bring them here? If these cars were sold in the US, people would get rid of their pick-ups and large trucks and get the exact same car they had, just a greener version. Maybe not right away because we are still in a recession, but over time people will realize that these types of cars will save them so much money. And, we would cut down our overall use of oil. I believe we sometimes forget that oil is becoming more and more scarce and that we depend on it way too much. So if Obama would pass some legislation or something to get these types of cars into the US, over the long run it would make a huge difference.