Corvettes doing 30 mpg... I am not convinced.
How about a challenge?
Write down your current mileage and from now on every time you fill up log the amount of fuel you put in. After a couple hundred miles check the mileage again to get the amount of miles covered. Then sum up the amount of fuel you used and calculate mpg (UK and US - they differ a lot).
You\'ll be lucky to get a figure anywhere near 20 US mpg for a Corvette.
I am carefully logging fuel spending on my Audi diesel and so far I am averaging below 6.5 l / 100 km. That\'s a lot of mpg :D