Advice from Intellichoice: Fuel Cost Overview

Fuel is the one expense a car owner faces on almost a daily basis. Of course you can reduce your fuel costs by driving more conservatively and logging fewer miles, but that’s often easier said than done. You can also buy a fuel-miserly car instead of a gas hog; the data on our site will show you which is which.

Keep in mind that if you buy a car with relatively poor fuel economy, your costs rise in three respects. First, there’s the acquisition cost, as models with large engines typically command a price premium over more conservative peers. Second, there will be the cost of the extra fuel. Third, a gas-guzzler tax imposed on the automaker by the federal government is included in the purchase price of the worst offenders. But beyond the type of vehicle you buy, there are other considerations in reducing fuel costs.

Selecting the Proper Octane

A car’s engine develops power because a mixture of gasoline and air is burned in the engine’s combustion chambers. If this mixture burns too rapidly, it results in explosions in the chambers. The engine won’t fly apart, but these explosions will set up vibrations that you will hear as a “knocking” sound, especially when you accelerate briskly. Inside the engine, the effect is like hammer blows to the top of the pistons. If the blows are severe enough, they can damage the engine. By matching the engine’s octane requirements to a gasoline’s octane rating, you’ll get a nice, even burn of the gas/air mixture. You can get an idea of your car’s octane requirements by looking in the owner’s manual. Unfortunately, finding the optimum choice of fuel for your car is not quite that simple. An engine’s octane requirements can vary according to its age, the outside air temperature, humidity and altitude.

This means you have to experiment with different grades and brands until you find one that eliminates knocking in your vehicle. But if your car doesn’t knock or ping when you use a regular grade of gasoline, don’t waste your money by “treating” your car to a more-expensive premium grade. Unless your car’s owner’s manual specifies premium gasoline or your car’s engine knocks on regular gasoline, using premium will not provide any advantages over a less-expensive regular grade. It won’t give your car more power and it won’t keep the inside of your engine any cleaner. Federal clean air rules now require oil companies to formulate their gasolines with additives and detergents to prevent internal deposits - no matter what the grade of gasoline.