I've got an '06 Corolla with an AT and have an average MPG of 40.40 tracked over 163,000 miles over 6 years So getting that kind of mileage is very doable. Here's my technique:
- Pump up the tires to 40 PSI.
- Place a corroplast air dam behind the upper grill piece along with a piece of corroplast to act as an air dam under front of the car.
- Run a length of 3" flexi-vent pipe to act as a WAI drawing air directly behind the radiator.
- Insulate the engine, I've got a piece of cardboard over the top of the engine to help retain heat/reduce warmup year round.
- Block off the radiator to the point that water temps run around 195 degrees. This needs to be adjusted periodically.
- Drive speed limit.
Most of the miles are highway as I commute 40 miles at 65 mph to work. The climate here is about 9000 DD so winter temps and snow has a definite toll, mileage in the winter drops to around 36 for me.