Keep track of your petrol mileage to make sure your car is not using more petrol than it was designed to use. You may not notice a big drop immediately, or even in a few months. But by keeping your car in good shape you will save dollars. Check your tyres to make sure they are properly filled. Low air pressure in your tyres means your car has to work harder to move along, and that eats up petrol.
Tyres lose pressure at different rates, so look at all the tyres on a regular basis.
Be sure not to over-inflate your tyres and make sure your tyres are also in good condition. Don't forget to have your wheels properly aligned as well. Change your fuel filter at least once a year. A fuel filter can get plugged with debris. This not only can slow the process of petrol getting to your engine, but it can stop your car cold if the filter is completely blocked and no petrol gets through.