My driving is pretty much even mixed in that I spend about 50% of the mileage in "city" driving and 50% in highway driving. We carpool so highway driving for us is a lot of 75mph with the cruise control set. I get 16mpg. Not calculated by the trip computer but using actual gallons pumped vs. odometer.
Pretty bad, IMO but about what I expected.
My biggest grip isn't so much the fuel efficiency, per se, but the fuel efficiency combined with a very, very small gas tank means I have to fill up a lot. That kind of sucks.
I've had fuel inefficient cars in the past but usually I'm still able to get at least 300 miles on a tank before filling up. I'm not running the M dry but I'm only getting 200 - 250 before the gas light comes on.
BTW - 6 speed MT