Fuel efficiency was one of the top considerations for most new car buyers in 2024. While some buyers may be looking for fuel efficiency to protect their wallets, others want to protect the environment. Either way, they'll use a vehicle's miles per gallon rating as a key factor in their decision. But what is mpg?
Learn more about this figure and discover how and why you should factor it in yourself. We'll also help you compare your mpg to other cars and offer tips for improving your miles per gallon to keep your wallet and the environment happy.
What Does MPG Mean?
MPG stands for miles per gallon and measures how far your vehicle can travel on one gallon of fuel. For example, a car rated at 35 MPG can drive 35 miles per gallon of gas. Most vehicles receive an official MPG rating, except for:
- Motorcycles
- Passenger vehicles over 10,000 pounds
- Cargo vans over 8,500 pounds
- Pickup trucks over 8,500 pounds with 72+ inch beds
The Environmental Protection Agency (EPA) certifies MPG ratings through road and lab tests, providing three measurements:
- Highway miles per gallon: Cars typically get a higher average mpg on the highway because they travel at a higher speed consistently for a longer distance.
- City MPG: City driving involves frequent starting and stopping and lower speeds, which decreases fuel economy.
- Combined MPG: This figure is an average of a vehicle's highway and city mpg.
These ratings appear on dealership window stickers (Monroney labels) and the EPA's fuel economy website.
How To Calculate Your MPG
Miles per gallon estimates are general figures that don't always reflect real-world driving conditions. To calculate your actual mpg:
- Fill up your gas tank completely and reset your trip odometer (check your owner's manual for instructions).
- Drive normally until the tank is nearly empty.
- Refill the tank and divide the miles on your odometer by the gallons used, which will be on your receipt or pump screen. For example, if you drive 375 miles and refill with 9.5 gallons, dividing 375 by 9.5 gives you an mpg of about 40.
Some newer vehicles can calculate mpg for you in real time and display the information on your dashboard or infotainment screen. This feature makes tracking your fuel efficiency simple and eliminates the need for manual calculations.
Knowing your mpg helps budget fuel costs and monitor your vehicle's performance. For example, if your car averages 30 mpg and you commute 30 miles daily, you'll use a gallon of fuel per day and need to refill a 10-gallon tank every 10 days.
If your mpg drops unexpectedly despite consistent driving habits, it may indicate an engine performance issue issue, so consider visiting a repair facility to address the problem early.
How To Convert MPG to L/100 km
Drivers in America use miles, but drivers in places like Canada and Europe use kilometers, so you'll need to know how to convert mpg to L/100 km. However, American gallons and European gallons are different. American gallons equal 3.79 liters, while European gallons are imperial gallons and equal to 4.55 liters.
If the miles per gallon figure is in imperial gallons, divide 282.5 by the miles per gallon figure. For example, if a car has an mpg of 40, you would divide 282.5 by 40 and get 7.1 L/100 km.
If the miles per gallon figure is in U.S. gallons, you'll divide 235.2 by the miles per gallon figure: 235.21/40 = 5.9 L/100 km.
What Is a Good MPG?
In general, the higher your miles per gallon, the better, and what is considered a good miles per gallon for one vehicle will not be the same for a different make or model. Instead, compare your miles per gallon to the U.S. average mpg, which in 2022 was 26 mpg, or the average gas mileage for your vehicle type.
Factors Influencing MPG
Miles per gallon is an average reflecting different factors that influence the fuel efficiency of a vehicle, so your actual MPG may differ from the official rating. Your MPG may be higher or lower depending on various factors:
- Driving habits: Aggressive driving, like quick acceleration and hard stops, lowers gas mileage. Hauling heavy loads or towing also reduces fuel efficiency.
- Vehicle condition: Newer cars often get better MPG due to advanced technology and well-maintained parts. Old oil, dirty filters or unbalanced tires can lower efficiency.
- Road conditions: Driving on flat, straight roads improves miles per gallon, while hilly terrain and frequent stops decrease fuel efficiency.
- Vehicle type: Larger and heavier vehicles tend to have a lower miles per gallon rating because they require more power to move. Other vehicle factors that impact your fuel efficiency include:
- Two-wheel drive versus four-wheel drive capability
- Hybrid drivetrain
- Sport versus eco or econ mode
- Engine size (measured in liters)
- Aerodynamics of the body
Understanding these factors and adjusting accordingly can help you optimize your vehicle's real-world fuel economy.
How to Improve Your MPG
Fortunately, improving your miles per gallon is possible by changing your driving habits and properly maintaining your vehicle.
- Plan the most fuel-efficient route for every trip. Many navigation apps will now offer an eco-friendly route in addition to the quickest.
- Combine trips when possible. Instead of driving across town to eat at your favorite restaurant, wait until you have another reason to drive that way, such as stopping at the pharmacy in the same shopping center.
- Follow your vehicle's maintenance schedule. Ensuring everything is in working order keeps your car performing at its best, which can increase your mpg.
- Only use the fuel recommended in the owner's manual. Using the wrong fuel can decrease your car's performance and fuel efficiency.
- Use cruise control on the highway. Cruise control maintains steady speeds, improving fuel efficiency. Newer models automatically slow down for vehicles ahead, preventing sudden braking that wastes fuel.
- Keep an eye on your tires. For best performance, check your tire pressure frequently to ensure your tires are properly inflated. Rotate your tires according to the manufacturer's recommendation and keep them aligned and balanced.
- Avoid accelerating excessively. When driving in the city, accelerate slowly and steadily and avoid sudden braking whenever possible.
- Remove excess weight from your car. Empty the trunk of everything you don't need and remove any outside storage like a roof box when you don't need it. One-hundred pounds of weight can decrease fuel economy by 1 percent.
- Use Eco or Econ mode. Modern vehicles often have an Eco or Econ mode that reduces the amount of power the engine produces. This means your AC won't run as frequently, and you won't be able to accelerate as quickly, but you improve your miles per gallon rating.
- Avoid idling. Idling burns fuel but does not move the vehicle, lowering your overall fuel efficiency. While some idling is unavoidable, some modern cars have automatic shut-offs that will turn the engine off while you are stopped and automatically restart it when you press the gas pedal.
- Stick to the speed limit. Every five miles per hour over 60 mph can decrease your vehicle's fuel efficiency by 7 percent.
By adopting these strategies, you can maximize your vehicle's fuel efficiency and save you money at the pump.
Keep Your MPG High With AAA
Get the best miles per gallon with regular maintenance to keep your car performing its best. Schedule an appointment at one of AAA's 7,000 approved auto repair facilities, which are only staffed by Automotive Service Excellence (ASE)-certified or factory-trained technicians. All work comes with a 24-month/24,000-mile warranty and fair pricing.
With your AAA membership for priority service and savings on labor costs for any repairs, or if you run out of gas, one of our roadside assistance providers will bring you enough gas to get you to the nearest gas station.