The mileage for my 1989 is fairly consistent at 17-18 mpg whether driving 55 or 75 on the highway with the top down, and that is with the engine in tip-top shape. I believe that is what the factory number is as well. Figured it would get better than that since it is such a small car, but it is also heavy with (what appears to me to be) an inefficient fuel injection system. And I like to 'gun it' more than I should as well. I've never checked it, but I suppose it would make a difference if the top is up or down due to aerodynamics.

That does look like a 1986 and 1987 trunk lid/center brake like. Bet the seller is not right on the year, unless it has been rear ended and it has been replaced. It did not come from the factory with the Euro headlights either.