There's no secret to getting the most from your car when it comes to gas mileage.  It comes down to maintenance. Keeping up on things like oil changes, belts and hoses can save you money. Every time you change your oil ask to see your air filter. If you have a dirty air filter it prohibits air to get through to the engine. This causes the mix between air and fuel to be unbalanced, so there will be more fuel in the engine. Outside of the engine, your tire pressure can also affect mileage.  If you are deficient in your tire pressure you have more rolling resistance with your tires to the ground which is not as efficient, causing decreased fuel efficiency. PurigeN98 high purity nitrogen inflation will help maintain the proper pressure in your tires over an extended period of time which will minimize tire rolling resistance. Using nitrogen in your tires as opposed to air can lead to better fuel efficiency because nitrogen molecules are larger and don't leak as easily.  The US government estimates that by maintaining the proper pressure within your tires, the average driver will save 3.3% on fuel use.
Goodyear Tires
Toyo Tires
Michelin Tires
Dunlop Tires
When a tire is properly inflated the rolling resistance is optimized. Ever cycle on a bicycle or push a wheel barrow with under inflated tires? It takes more energy to push forward. For every 10% the tire is under inflated, it uses 2% more fuel. So a tire that is supposed to be inflated to 32 PSI with only 26 PSI uses 20% more fuel. Considering today's high fuel prices, underinflation can be very costly.