Fuel efficiency is an important issue for car buyers, and understandably so. Conserving fuel is good for drivers' budgets and the planet, so the concept of fuel efficiency would seem to benefit everyone.
But just because fuel efficiency is a good concept does not mean there are not misconceptions about it among drivers and automotive professionals alike. The following are some of the more widely held misconceptions about fuel efficiency.
* Full tanks conserve fuel. Many people have long believed that a nearly full tank of gas means the fuel within that tank is less likely to evaporate, and that tanks that half-full tanks are losing gas to evaporation. Though this might have been the case years ago, today's vehicle's are smarter than ever before, and their fuel systems are designed with vapor recovery systems so drivers traveling around with tanks that are closer to empty than full aren't losing gas to evaporation.
* Manual transmissions are more fuel efficient. Technology can once again be credited with turning conventional wisdom on its head. In the past, manual transmission vehicles might have been more fuel efficient because drivers could more efficiently control engine revving with a 5-speed manual transmission than they could with the standard 3-speed automatic transmission. However, automatic transmissions have evolved over the years, and they are now more adept at controlling revs and conserving fuel than many drivers of manual transmission vehicles.
* When you fill up matters. Some drivers have long believed that filling up during the cooler hours of the day earns them more gas than filling up when the temperatures are at their peak. This theory traces its origins to the fact that liquids are at their most dense when they are cool. But today's filling stations store their gas in tanks beneath the ground, which is why you might see a tanker emptying its contents into the ground at the filling station. These underground tanks are insulated from temperature swings, so you aren't likely to receive any more gas by filling up in the morning than you will when filling up at night.
* An old vehicle is destined to be less fuel efficient. Any product that is allowed to fall into disrepair will prove less efficient than products that are well maintained, and cars are no exception. A poorly maintained car will not operate at peak fuel efficiency because it's likely being forced to work harder to get down the street than it would if it was well kept. But a well-maintained vehicle should not grow less fuel efficient over time.
* Shifting into neutral while stopping saves gas. This is another misconception that was once true but no longer applies thanks to advances in technology. When engines still had carburetors, shifting into neutral might have helped conserve fuel by stopping the flow of gas into the engine while the car was idling. However, fuel injection systems are now computerized and capable of sensing when an engine is revving above idle. This shuts off the fuel injectors, preventing gas from being injected into the engine and preventing gas from being wasted while the vehicle is stopped as a result.
Taking steps to conserve fuel is a good way for drivers to save money and benefit the environment. However, some of the conventional means to conserving fuel are no longer viable.