Quick answer: MPG means miles per gallon, the distance your car travels on one gallon of fuel. A higher MPG number means your car uses less fuel for the same distance. You can improve your real world MPG by driving smoothly, keeping tires at the correct pressure, removing extra weight and drag, and keeping the engine properly maintained.
Understand What MPG Really Measures
MPG is a simple ratio. Take the miles you drive, divide by the gallons of fuel you use, and you get miles per gallon. That ratio lets you compare cars and driving styles in a way that a single tank of fuel cannot, because tank size varies from car to car. To measure your own MPG honestly, fill the tank fully, reset your trip meter, drive normally, and at the next fill note the miles driven and the gallons added. Divide miles by gallons for that tank. Repeat over several tanks and average the results, because one tank can be affected by traffic, weather, and how full the tank really was. A single tank that looks unusually good or unusually bad is not a verdict on your car. A trend over several tanks is. That trend is the number you should use when you decide whether a driving change or a maintenance job actually helped.
Drive Smoothly and Keep Speed Steady
Driving style is the largest factor you control day to day. Hard acceleration and hard braking waste fuel, because energy spent building speed quickly is then lost when you brake hard. Smooth acceleration, looking far ahead in traffic, and easing off the accelerator early when traffic slows will keep your car moving with less wasted energy. FuelEconomy.gov notes that sensible driving can save a meaningful share of fuel compared with aggressive driving, and that each rise in speed above highway cruising speed lowers mileage further. Use cruise control on flat, open highway stretches when it is safe to do so, because it holds a steady speed better than a human foot can over a long distance. In heavy traffic, leave a larger gap ahead, so you can slow gently instead of braking sharply. That gap is not wasted space. It is the space that lets you keep momentum and avoid a stop and start cycle that burns the most fuel.
Check Tires, Weight, and Drag Every Week
Underinflated tires increase rolling resistance, which means the engine must work harder to move the car the same distance. FuelEconomy.gov notes that underinflation lowers mileage by a small amount for every pound of pressure lost across all four tires, and that effect adds up when pressure stays low for weeks. Check pressure when tires are cold, use the pressure shown on the door sticker or in the manual rather than the maximum shown on the tire sidewall, and recheck after a sharp temperature change. Remove weight you do not need for the trip, especially heavy items left in the trunk for weeks. Remove a roof box or roof rack when you are not using it, because it adds drag at highway speed. Close windows at higher speeds and use air conditioning in moderation, rather than driving with windows open at highway speed, which also adds drag. Our guide on how to check tire pressure gives a simple routine you can follow in a few minutes. Small checks done regularly beat a single large effort done once a year.
Keep the Engine and Fluids in Good Shape
A car that is out of tune wastes fuel in ways that are easy to miss. A dirty air filter restricts airflow, worn spark plugs can cause incomplete combustion, and the wrong grade of motor oil can increase friction inside the engine. Follow the service schedule in your manual for oil, filters, and spark plugs, and fix a warning light promptly rather than driving for months with a fault that affects combustion. FuelEconomy.gov notes that fixing an out of tune engine can improve efficiency by a few percent on average, and that using the wrong oil grade can lower mileage by a small amount. Those gains sound small on their own, but they combine with driving style and tire pressure to make a real difference over a year of driving. If your MPG drops suddenly, treat that drop as a symptom. Check tire pressure first, then look for a new noise, a warning light, a dragging brake, or a change in how the car starts and idles. A sudden drop often points to a fault that needs attention, not to a change in your driving.
Plan Trips and Cut Cold Starts
Short trips from a cold start use more fuel per mile, because the engine runs less efficiently until it warms up. Combining errands into one trip, rather than making several separate short trips, reduces the number of cold starts and the total miles driven. Plan your route to avoid heavy traffic where you can, because idling and crawling in traffic return no miles for the fuel burned. Turn the engine off when you are stopped for a longer wait and it is safe to do so, rather than idling for many minutes. When you buy your next car, compare MPG on a like for like basis, using the same driving pattern you actually do. A car that is efficient on the highway may not be the best choice if most of your driving is short city trips, and a car that looks efficient on paper may not match your real world use. Use your own measured MPG trend, not a single advertised figure, to judge whether a change in car, driving style, or maintenance is actually paying off. For a broader view of running costs, read our cost of vehicle tune up guide and decide which maintenance jobs give the best return for your car.
Set a Realistic MPG Goal
Set a goal you can measure, not a vague wish to use less fuel. Record your MPG for four tanks as a baseline, then change one habit at a time and record four more tanks. Change driving style first, because it costs nothing and often gives the largest gain. Then fix tire pressure and remove extra weight. Then complete any overdue maintenance. If MPG improves and stays improved, keep the change. If MPG does not improve, look for a mechanical cause rather than blaming your driving. Keep a simple log with date, miles, gallons, and MPG, plus a note about the kind of driving in that tank, such as mostly highway or mostly city. That log turns fuel economy from a guess into a decision tool. It tells you when a repair is needed, when a driving habit is working, and when a new car claim is worth believing. Fuel economy is not about driving slowly at all costs. It is about driving smoothly, keeping the car in good shape, and removing waste that gives you nothing in return.
Questions and Answers
What is a good MPG figure?
A good MPG figure depends on the size and type of car and on how you drive. Compare your car with similar cars and with your own trend over several tanks, rather than judging it against a much smaller or much larger vehicle.
How do I measure my own MPG accurately?
Fill the tank fully, reset your trip meter, drive normally, and at the next fill divide miles driven by gallons added. Average the result over several tanks for a reliable figure, and note whether each tank was mostly city or mostly highway driving.
Does driving slower always improve MPG?
Driving at a steady and moderate speed usually improves MPG compared with speeding and with constant speed changes, but driving far below the flow of traffic is not safe and is not the goal. Aim for smooth and steady driving at a sensible speed for the road and conditions.