17!
Still, I guess you don't mess about with eco driving tactics.
That said, its only 8 less than when I go for a spirited weekend drive... And I have half the cylinders and less than half the displacement!
For what it is it is good, because it is matches the 911 with two more cylinders and more weight to lug around and on a run it can achieve over 30mpg which is better than the 911, so economy is way beyond my expectations of 11-14 day to day and around 25 on a run.
Plus fuel is much cheaper, servicing cost is absolute peanuts and insurance is also peanuts, not only is the car incredible value it also cost very little to run for a V8 and the performance it offers.
Yes it would be nice if it had some of the neat touches the GM cars have such as 4 cylinder eco mode (4 cylinder shut down) along with a decent modern DCT/Auto style box but small niggles and I enjoy driving it so much and I just stand looking at the car, always looking back at it and taking photos. Out of all the cars I owned only my past Mustang and the 911 I could just simply look at because they looked so damn good.