increase your average / mileage

I think to increase mileage, the best approach would be to tune your driving habit. How is that? Do not accelerate too quickly as that requires more horse power from your car and that burns more fuel. When you are approaching the traffic lights, release the gas pedal earlier if you expect the light is red. The need for pressing the brake means you need to "waste" the extra energy you have allowed the car to pick up (which in turn means you have stepped on the gas pedal longer than you actually need it). As long as you can maintain a relatively stable acceleration/deceleration, the extra fuel burnt should be minimized. Also, there are studies showing that mileage is better at around 100km/h. Anything higher will actually be less fuel efficient.

i think, you should not try and strain your engine, i mean drive your car at a normal speed don't hit the gas paddle like mad and increase your speed, drive at around 30-40 miles an hour and you will definitely increase your mileage, another thing is that you should always check the tyre pressure regularly and also switch off the car at a red light.