Mainly I am talking about the V8 here, since that is all I am interested in... so I did a little research.
The 2005 Pontiac GTO is the closest comparison I could think of, so I looked into it a bit:
According to <http://www.fueleconomy.gov/feg/noframes/21556.shtml>
The 2005 GTO gets
Fuel Type: Premium
MPG (city): 14
MPG (highway): 19
MPG (combined): 16
Annual Fuel Cost $3000 (15K miles @3.20/gallon)!
Other folks at <http://www99.epinions.com/content_174299516548> are reporting 25mph on the highway... which seems somewhat better.
What experience to you have? What mileage do you get in your 4th, 3rd, 2nd or 1st gen?
I'm not looking to save the planet, just to set up my budget accordingly...
~LSx