This has been posted for a while, but I just came across it. PopMech wanted to see what kind of fuel economy was possible from a C7 Corvette. So, they took a 55 mph cruise in Eco mode and averaged over 37 mpg over 124 miles. Pretty impressive for a car as capable as the Corvette!
See Taking the 2014 Chevy Corvette on a Fuel-Economy Run