For those who already own or drive the same vehicle consistently, the need to estimate MPG may be a critical factor in determining how the car is performing. In most cases finding a way to estimate MPG is not a big problem. Most people can do it with some very simple math. In some cases, it seems like individuals are able to estimate MPG better than groups charged with publishing those estimates for new cars.
The easiest way to estimate MPG is to fill up the tank, then keep track of the number of miles driven before stopping to refuel. It is not necessary to drive until the gasoline tank is almost empty to estimate MPG. Rather, this can be done almost at any stage of the process. The greater the distance between refuelings, the more accurate the numbers will be. Once the driver has stopped to refuel, take note of the miles driven since the last fill up, and the number of gallons it takes to fill the car up. Then divide the miles by the number of gallons and an estimated gas mileage has been produced.
With fuel prices becoming a big concern, more people are wanting to estimate MPG, and it can be a useful diagnostic tool. For example, those who consistently see a noticeable decline in gasoline mileage may have mechanical issues, which causes the vehicle to work harder and burn more fuel. These issues may be minor, taking very little money to correct, such as improperly inflated car tires, or they could be very major.
Some have also openly wondered how the United States Environmental Protection is able to estimate MPG numbers that seem so different than what is actually achieved in real-world fuel economy. While these estimates have received a lot of criticism from new car owners, there is actually a reason for the EPA's estimate. The agency tests vehicles under normal driving conditions for the 1970s. Among the most notable differences is the fact the speed limit was only 55 miles per hour (mph) then.
Starting with 2008 model years, the EPA began a new method for determining an estimated MPG. Among changes made were testing a higher speeds with more aggressive acceleration, along with testing in different weather conditions with the air conditioner or heater operating. In some cases, this may reduce the EPA mileage estimate by as much as 30 percent. Many claim this will give consumers a much more accurate picture of the miles per gallon estimate.