On flat highway, at 70mph, my DIC says 28-30 mpg. I do 3/4 highway and normally my DIC average at fill up time is 24-25. pyromaneyakk is always passing me.
I love the news reports that say everybody is worried about raising gas prices. I set my cruise at 65-70 on the freeway to work. There are a lot of cars and trucks that fly by, probably even a few Silverado SS (hot). Yeah, they are really concerned about fuel prices!!! My crazy driving is mixed in with some really conservative driving....Coast to the lights...Use the cruise...Lights are timed at around 42 mph in Mesa AZ.
If you are really concerned, you wouldn't be asking about a V. If you want to go fast and get decent mileage, then get a Cobalt SS. The new Malibu is decent, but the one with our 3.6 motor gets about the same mileage as a CTS. Actually, the Vette (even C5) has great mileage ratings (if you could stay off it).
I would love to trade my CTS for a V, but fuel mileage, and having to buy premium, is one downside. Our 3.6s are not blazing fast, but they are fast enough to have some fun in. Besides, the handling is great.
Dan