Theres a guy local to me who has a 400+whp 2.3 turbo and he gets 30-35 mpg on the highway and mid 20's in the city. Don't tell me that's barely better than a 5.0, lol. I have one myself as well and they aren't too bad on gas really.
The more I thought about this the funnier it seems as 400 HP at the Wheels would be about 500 Engine HP, so this guy is saying he puts down more power than a new Vette and yet gets the economy of a Toyota Corolla, I would think the Car Manufacturers would be trying to find this Guy so they can figure out what they are doing wrong and what he is doing right!
I've driven across Arizona on I-8 using slightly less than a full tank, which I thought was pretty impressive. I would fill up in Yuma and not have to stop again for fuel until I was getting off I-10 in Lordsburg, NM to head north to Silver City.
buy a turbo diesel and then steal all the french fry grease from mcdonalds and run bio diesel. it's free and you get 30mpg. but you and your car will smell like burgers and fries for the rest of your life.