Your SVT has issues then - big V8 vs small I4 is not a comparison. Grats if your Dad's C6 gets better MPG - must be one of those grey haired folks I see driving the speed limit in Vett's all the time...
23-25 in town on the way to work and 29 on the highway at 80...and my father does not have gray hair. Not completely at least. If you think there is something wrong when I get the same or slightly lower numbers in my SVT, you should look at some of the mileage threads around here.