At one point, we all need to make one of life's most important - and exciting - decisions: which car to buy. With the plethora of models available on the market today, catering to every budget, taste and whim, it's quite difficult to choose. While the criteria vary from one person to the next, the one thing everyone is looking for in the post oil-abundance era is fuel efficiency. But what is it that makes one car more fuel efficient than another? First, some basic mechanical facts. Fuel is burned in the engine to produce mechanical energy to power your car. Therefore, fuel consumption factors are related to the engine and the body of the car. In simple terms, bigger engines consume more fuel. In other words, the bigger the engine displacement (the volume of which is often measured in cubic centimeters, or cc), the higher the fuel consumption. However, there are two exceptions to this rule. If an engine is too small, it requires double the fuel to produce the same amount of power. Also, if the engine is supercharged (with a turbo or a compressor), it will consume more fuel and produce much more power, which equals better efficiency. It sounds a lot simpler than it actually is; internal combustion engines are complex technological objects, with a labyrinth of small pieces working together. Much of the research and development efforts made by automakers go into finding ways to make engines more fuel efficient by reducing friction and the weight of engine parts and adopting more precise admission and exhaust systems. When looking at the engine specs of a new car, it is better to avoid engines that are too big or too small (less than 1,000 cc or more than 3,500 cc). You also want to pay special attention to the technology of the engine itself. BMW and Honda have the greatest repute in this regard, but generally, most new models from well-known European and Japanese carmakers have good fuel efficiency. On the other hand, American manufacturers have the unfortunate reputation of producing "gas-guzzlers, while Chinese and Indians carmakers - newcomers to the industry - have not yet mastered the technology to be able to compete with state-of-the-art standards. The body of the car can also significantly influence fuel consumption. The heavier the automobile, the more power required to move it, which translates into higher fuel consumption. Optional features such as the A/C, electric windows, airbags, sophisticated sound systems and all the extra electronic gizmos that make cars comfortable and secure, also add weight to the body. In modern cars, it is common to use lightweight materials to improve fuel efficiency. The design of the car also affects fuel efficiency, namely the curves and turns that determine its resistance to air. The more aerodynamic the shape, the less air resistance it has, which makes for a smoother ride and lower fuel consumption. A slender sedan, for example, is more aerodynamic than a cubic off-roader. Once you've considered these basic factors when choosing a new car, you're ready to roll. But remember, the way you handle and take care of a car also affects fuel efficiency. Properly inflated tires are key to both fuel efficiency and safety. Deflated tires generate more friction with the asphalt and require more power (i.e. fuel) to move. Old and viscous engine oil needs more work to set the different parts of an engine into motion, thus burning more fuel. So to keep fuel consumption at a reasonable rate, watch the air in your tires and the oil in your engine. At this point, we can conclude that modern, mid-sized, European or Japanese cars are the most fuel efficient and that proper maintenance is essential. However, this would ignore the most influential agent: the driver. The way you drive can either double fuel consumption or lower it dramatically. Vigorous acceleration and intensive braking, as well as running the engine in high regimes (measured in RPM) ups fuel consumption, while smooth driving and proper gear shifting improve efficiency. One widespread misconceptions concerns A/C usage. Many say that turning on the A/C dramatically increases fuel consumption, and prefer to drive with the windows down. While this may be true for low speeds, once you're on the highway, the increase in air resistance created by opening the windows leads to higher fuel consumption than turning on the A/C.
