If you absolutely need to drive a car, consider to review your driving habit (I know it's kind of very hard) as it will affect your gas mileage per gallon. The optimized speed for the maximized highway MGP depends on the model of your car. However, in general, if you're on a highway going over speed limit, you're absolutely not getting the best MPG and may be off by five percentage, ten percentage, or even more. It might be too trivial to remember the exact speed to drive for getting the best MPG, but if you can reduce aggressive speeding and don't drive over highway speed limit, which you shouldn't anyway, you'll be stretching your gas mileage in the right direction.
Remember to keep tires properly inflated. If tires are under inflated, they may cost you up to 4% of fuel efficiency according to U.S. Department of Energy. On the other hand, over inflated tires may increase blow out risks. You want your tire pressure to just about the manufacture's suggested PSI (pound per square inch) which is available on the sticker on the driver's door side. I recommend using a non-digital air pressure gauge (e.g. a Handheld Dial Tire Air Pressure Gauge) for measuring tire pressure. A non-digital air pressure gauge does not require battery thus it is always ready for measuring tire pressure when you need it. Besides, non-digital air pressure gauges tend to cost less than the digital ones. American Tire has an online Tire Pressure Gas Mileage calculator that tells how much is low pressure tire costing you.w
Lastly, evan you can't possibly avoid using gas, consider this: When I pay at the pump, if I chose to pay with a credit card, I always opt for using the card that gives me some money back on gas purchase. For example, the AE card I have gives me 3% cash rebate on every dollar I spend at any gas pump. You may consider the same approach because every little bit of saving counts.
by Charles Gwa