According to "Time" magazine, one of the first cars--the Ford Model T--achieved a fuel efficiency of about 21 miles per gallon. However, fuel efficiency decreased after this because cars gained power, and gasoline was so plentiful and cheap that most people did not care. Now that the world faces dwindling gas supplies, people are trying to find ways to make their cars more efficient.
The internal combustion itself is not very efficient, losing about 62.4 percent of the energy from gasoline just from engine losses, according to the U.S. Department of Energy and Environmental Protection Agency's Fuel Economy. A car loses another 17.2 percent due to idling and 7.8 percent from other losses. In total, only about 15 percent of the energy from gasoline goes toward moving the tires.
The fuel efficiency estimates provided by the U.S. EPA are not always accurate, according to "USA Today." EPA estimates are based on optimal driving conditions and do not take into account things like driving in cold weather and making short trips that waste gas. In addition, only 15 percent of vehicles are actually tested for efficiency--the rest are based on company paper calculations.
You may also waste gas due to the way you drive. Rapid accelerating and decelerating reduces your car's efficiency by 33 percent on highways and 5 percent on city streets, according to Fuel Economy. In addition, driving only between 40 and 60 mph gets optimal gas mileage. Idling wastes the most gas because you get zero mph.
According to CarMax, the Lexus requires you to use premium gasoline if your car owner's manual says to use it. Using a lower-grade gas reduces your fuel efficiency by up to 6 miles per gallon. However, no information exists on whether this occurs in all car makes and models.
You do not need to "warm up" your engine--you will see no benefits, according to Yahoo! Autos. Start accelerating gently to warm up your engine. In addition, do not always aim to drive between 40 and 60 mph unless it is within the posted speed limit--your safety is worth more than gasoline.
