27-30 sounds overly optimistic for the car.
You can get as close to new gas mileage with a tune up though.
Check for old plugs, wires, and proper coolant temperature when warm.
My car was running 10% rich and I discovered that it was because a bad thermostat was forever keeping the car in "warming up mode".
I didn't improve the gas mileage from stock, but I did recover quite a bit of it.
Last edited by justflick; 04-04-2012 at 08:11 AM..