• Check your owner’s manual to find out what fuel octane-rating your car's engine needs, then buy it. Resist the urge to buy higher-octane gas for “premium” performance. Octane has nothing to do with the gasoline’s performance, just its volatility factor in the combustion chamber. The higher the octane, the more stable the gas in the combustion chamber environment. Why do high-performance vehicles need higher-octane fuel? Because the combustion chamber environment is much hotter in the performance engine. Using high-octane fuel reduces pre-ignition in the upper regions of the combustion chamber, which can damage valves and pistons if allowed to go for long periods of time. Experts from the Automobile Association of America (AAA) say that about five percent of the cars sold in the U.S. require premium gasoline. Yet premium gas accounts for 20 percent of all gasoline sold. Check your owner’s manual for the recommended octane rating and stick to it.

• Keep your tires inflated to the proper levels. Properly inflated tires suffer less rolling resistance and therefore can improve fuel efficiency by making it easier for your car to move down the road. Under-inflated tires will make it harder for your car to move down the road, which means your engine uses more fuel to maintain your speed. A single tire, under inflated by two pounds per-square-inch (PSI), increases fuel consumption by one percent. To illustrate the point, deflate your tires by five PSI and try to push the car. It’s not easy. Now inflate those tires and see how pushing the car is much easier. Check your owner’s manual or the decal in your car’s doorjamb for correct inflation levels.

• Make sure that you change the oil and maintain your car’s powertrain according to your owner’s manual. This will ensure that your car’s engine will operate at maximum efficiency, thus providing the best fuel economy. Dirty air filters, old spark plugs and low fluid levels can affect engine performance and fuel efficiency. A properly-maintained engine uses less gas.

• Consolidate your errands so you can do them all in one trip. This will cut your total miles driven. Many people drive back and forth between destinations. Plan ahead. Set up your errands in succession and save gas.

• Modify your driving habits. Public roads are not racetracks. Don’t race up to red lights or stop signs, avoid quick “jackrabbit” starts, and stop goosing the throttle to jump into holes in traffic. A car uses more fuel under hard acceleration. And if you own a “full” hybrid vehicle that can operate at low speeds on the battery pack, this is especially important. The more you depress the accelerator, the more demand you make on the hybrid powertrain, and the earlier the gasoline engine will kick in and start consuming fuel.

• Avoid high speeds on the highway. As your speed increases, the aerodynamic drag increases in exponential fashion, so the engine works harder to maintain your speed and move the car through the atmosphere. The harder the engine works, the more fuel it uses. Driving 62 mph instead of 75 mph can reduce fuel consumption by as much as 15 percent. This is one reason why some hybrids get lower fuel economy on the highway than in the city.

• Lighten the load. Don’t haul unnecessary weight in the passenger compartment or trunk. Heavier vehicles use more fuel.

• Use the A/C sparingly. The air conditioner puts extra load on the engine, forcing more fuel to be used. On average, a car operating with the air conditioning engaged uses about 20 percent more fuel.

• Keep your windows closed. Open windows, especially at highway speeds, increase aerodynamic drag and the result is up to a 10 percent decrease in fuel economy. If you must have fresh air coming into the vehicle, run your climate system on ‘outside air’ and ‘vent’, and crack the window for additional ventilation.

• Consider getting a tonneau cover or a tube-style tailgate for your pickup truck. These items will help to minimize drag over the cargo bed and allow the vehicle to slip through the air stream more efficiently.

• Use your cruise control. Maintaining a constant speed over long distances saves gas. The next time you drive without cruise engaged, note how your speed creeps up and down. Constant deceleration, followed by acceleration, uses more fuel. The cruise control feature keeps your speed constant, saving gas (and maybe a speeding ticket, too).

• Avoid long idling. If you anticipate being stopped for more than one minute, shut off the car. Restarting the car uses less fuel than letting it idle. For most hybrids, this is not an issue, because the gasoline engine automatically shuts down when the car is stopped, and the accessories – such as the air conditioning, lights, and stereo – operate off the juice stored in the battery pack. This is also one reason that hybrids often get better fuel economy in the city than on the highway – the gasoline engine is shut off when idling in traffic.

• Consider purchasing a fuel-efficient vehicle, but only if you’re planning to replace your current car anyway. You might want to consider downsizing just a bit. By this we don’t mean selecting a smaller engine for the same size vehicle. Instead, get a smaller vehicle. If you select the smallest engine available for a larger vehicle, you will end up using more fuel because the smaller engine has to haul the same weight as the larger engine, therefore it has to work harder and might use more gas. For example, a pickup truck with a V8 could get better gas mileage than a comparable truck with a V6, because the more powerful V8 works more efficiently to move the truck’s mass.

Excerpt from Autosite.com

— CStingray78

• Use the A/C sparingly. The air conditioner puts extra load on the engine, forcing more fuel to be used. On average, a car operating with the air conditioning engaged uses about 20 percent more fuel.

• Keep your windows closed. Open windows, especially at highway speeds, increase aerodynamic drag and the result is up to a 10 percent decrease in fuel economy. If you must have fresh air coming into the vehicle, run your climate system on ‘outside air’ and ‘vent’, and crack the window for additional ventilation.

• Consider getting a tonneau cover or a tube-style tailgate for your pickup truck. These items will help to minimize drag over the cargo bed and allow the vehicle to slip through the air stream more efficiently.

Excerpt from Autosite.com

All three of these were proven wrong by myth busters. A/C On, Windows Down, and Tailgate shut all have no effect on miles per gallon. Actually I think their findings showed just the opposite.

Jeremy

Dude, Myth Busters rocks I didn't know they tested these theories.

i saw that episode but iu have to say in my ram i was getting 16-17 mpg on average then i got the tonneau cover and it went up to 21 mpg easily so i dont really know for sure