What Is Fuel Efficiency? (2024)

Fuel efficiency vs. fuel economy

There are different ways to measure and discuss a vehicle's fuel consumption. Fuel efficiency describes the vehicle's fuel consumption performance. Fuel economy, on the other hand, is a specific number. In America, fuel economy is expressed in miles per gallon. Other countries define fuel economy using different measurements such as kilometers per liter. The United Kingdom uses miles per gallon, but the imperial gallon is larger than the American one.

Experts recommend comparing fuel consumption to understand a car's real fuel efficiency.

Example:How to use fuel consumption numbers. If you pay an average of $4 per gallon of gas and your car uses 5 gallons per 100 miles (or 20 mpg), you'd spend $20,000 on gas over the course of 100,000 miles. In a car that uses 4 gallons per 100 miles (or 25 mpg), you'd spend $16,000 on gas to cover the same distance — a savings of $4,000.

Should I buy a more fuel-efficient car?

A more fuel-efficient car will pollute less and cost less to run. If reducing your environmental impact is important, getting a more efficient car is an obvious choice. If you're torn between two options, compare how much you'd spend on fuel over each car's lifetime to see if one represents a better value. Finally, if you want a more fuel-efficient car to save on running costs, you might consider buying a diesel car with a diesel engine, especially if you regularly put in lots of miles on the highway.

Benefits of fuel-efficient cars

Fuel-efficient cars emit less pollution over the same amount of distance traveled. They also cost less to operate. Buying a more fuel-efficient car can save you thousands of dollars on fuel costs over time and can often balance out a higher purchase price if you keep the car long enough. Fortunately, fuel efficiency has improved greatly due to tires, aerodynamics, body construction, and engine and transmission technology developments. According to Energy.gov, average fuel economy is now higher than 25 mpg, with many vehicles averaging more than 33 mpg.

Learn more about the differences between hybrid vs. gas cars and hybrid vs. electric cars and if they might be right for you.

How can I maximize my car's fuel efficiency?

The "mpg" number reported by car manufacturers is the result of testing conducted by the EPA. It represents an easy way to compare the fuel efficiency of cars, but it's not a guarantee. Real-world factors affect how far you go on a gallon of gas. The following driving and maintenance habits can help you make the most efficient use of your car:

• Check your tire pressure: Under- or over-inflated tires can reduce your car's efficiency.
• Drive calmly: Rapid stops or starts cause the engine to work harder and waste fuel. Increase speed gradually, even if you're in a hurry.
• Avoid very high speeds: All cars have a most efficient speed based on their tires, aerodynamics, and engine. While that exact speed changes from car to car, efficiency may decrease once you go above 50 mph.
• Don't idle (except in traffic): If you're waiting in a parking lot or otherwise sitting still in your car for more than one minute, it's more efficient to turn the car off than to idle.