I've never bought a car for the mileage to be honest. That said I do keep track of it oddly enough. I bought my '12 roadster in May and was getting about 16 mpg (US gallons) to begin with. At slightly over 2k miles now it sits at 19 right now with my mix of freeway/city driving which is spirited to say the least. I'm out to have fun and the mileage doesn't factor into my enjoyment.
In short it will improve so don't sweat it and enjoy!
