• Keep your car clean. Mud on the undercarriage can weigh a significant amount and slow you down.
• Consolidate your daily trips and errands. This will also save you the cost of restarting your engine, which uses a lot of gas.
• Avoid air conditioning when possible. However, when driving at higher speeds, having your windows open also creates drag.
• Don’t throttle the gas or brake! Sudden starts or stops use more gas than gradual changes of speed.
• Don’t idle for too long. Turn off the engine if you anticipate a lengthy wait. Limit car warm-ups in winter.
• Clear out the trunk. More weight, more drag.
• Avoid high speeds. We know this is almost impossible to resist but you can improve your gas mileage about 15 percent by driving at 55 mph rather than 65 mph.
• Use overdrive. If your car is equipped with overdrive gearing use it as soon as your speed is high enough.
• Use cruise control. Keeping a constant speed is ideal for improving your gas mileage.

• Improve the spark to your engine. This way, the air and fuel mixture will be burnt better.
• Improve your intake/output system. Helping gas get in and exhaust out of your vehicle will improve overall performance and gas mileage.
• Reduce friction. Use high-quality or synthetic motor oil.
• Check your oil! Low oil makes your engine work harder.
• Change your filters. Dirty filters can sometimes increase the amount of fuel your vehicle is using by 10 percent.
• Keep tires properly inflated and aligned. Check regularly to ensure your wheels are fully inflated and your alignment is good.
• Get regular engine tune-ups and car maintenance checks. A lot can go wrong with a car. Damaged spark plugs or transmission problems can also contribute to poor gas mileage.

Manual Transmissions:
Some older import vehicles (like Volkswagen Beetles) recommended periodic lube changes for their gearboxes, but no modern car or light truck requires it. The reason why is the oil stays relatively clean and runs fairly cool. Unlike the fluid in an automatic transmission that is being constantly churned (which generates heat) and contaminated by particles worn off the clutch plates, the fluid in a manual transmission or transaxle has life pretty easy. So it usually lasts the life of the transmission.The only reason you might change the fluid would be if you were experiencing hard shifting problems during cold weather. Most older rear-wheel drive transmissions use a heavy gear oil like 75W, 80W or 90W, which can get pretty stiff at subzero temperatures. Changing to a lighter oil may improve shifting.

Automatic Transmissions:
According to the Automatic Transmission Rebuilders Association, 90% of ALL transmission failures are caused by overheating. Most of these can be blamed on worn out fluid that should have been replaced. For optimum protection, change the fluid and filter every 30,000 miles. What kind of automatic transmission fluid should you use in your transmission? The type specified in your owner's manual or printed on the transmission dipstick. For older Ford automatics and certain imports, Type "F" is usually required. Most Fords since the 1980s require "Mercon" fluid, which is Ford's equivalent of Dexron II. For General Motors, Chrysler and other imports, Dexron II is usually specified.