Fuel Economy: How to Get Better Gas Mileage and Save Money

Why Fuel Economy Matters

Fuel is one of the largest ongoing expenses of vehicle ownership in America. With the country's car-dependent infrastructure and long commuting distances, even small improvements in fuel economy add up to significant savings over time. Understanding what affects your gas mileage — and how to improve it — puts money back in your pocket every time you drive.

Buying a used vehicle? Always check the VIN first. A vehicle's mechanical condition directly affects its fuel economy — problems hidden from view often show up at the gas pump.

Understanding MPG

In the United States, fuel economy is measured in miles per gallon (MPG). Every new vehicle sold in America has an EPA fuel economy rating, which provides city, highway, and combined MPG estimates. These are useful for comparison, but real-world fuel economy is typically ten to twenty percent lower than the EPA estimates due to more varied driving conditions.

City MPG reflects stop-and-go driving with frequent braking and acceleration. Highway MPG reflects steady-speed cruising. Combined MPG is a weighted average — roughly fifty-five percent city and forty-five percent highway.

What Affects Fuel Economy

Engine and Drivetrain

Engine size and type. Larger engines generally use more fuel, but modern turbocharged small engines can match the power of larger naturally-aspirated engines with better economy. Hybrid and plug-in hybrid powertrains offer the best fuel economy for non-electric vehicles.

Transmission. Modern automatics with eight, nine, or ten speeds are highly efficient. CVTs (continuously variable transmissions) are often the most fuel-efficient conventional transmission type. Older four-speed automatics are the least efficient.

Drivetrain. Front-wheel drive (FWD) is more fuel-efficient than all-wheel drive (AWD) or four-wheel drive (4WD). AWD systems add weight and mechanical friction. If you do not need AWD, choosing FWD saves fuel.

Vehicle Characteristics

Weight. Every extra hundred pounds reduces fuel economy. A midsize sedan gets better mileage than a full-size SUV partly because it weighs significantly less. Do not carry unnecessary cargo.

Aerodynamics. At highway speeds, aerodynamic drag is the dominant force your engine fights. Roof racks (even empty ones), cargo boxes, and open windows at highway speed all increase drag and reduce mileage.

Tires. Under-inflated tires increase rolling resistance and reduce fuel economy. Low-rolling-resistance tires (common on hybrids) improve economy. Wider tires and aggressive off-road tires reduce economy.

Driving Conditions

City vs Highway. Stop-and-go city driving uses significantly more fuel than steady highway cruising. Traffic congestion makes it even worse — idling and constant acceleration/deceleration are fuel economy killers.

Temperature. Cold weather reduces fuel economy — the engine takes longer to reach efficient operating temperature, cold air is denser (more drag), battery performance drops (affecting hybrids), and winter fuel blends contain less energy. Hot weather also reduces economy if air conditioning is running constantly.

Terrain. Hilly terrain requires more fuel than flat roads. Mountainous driving increases fuel use significantly.

How to Improve Your Gas Mileage

Driving Habits — Free and Effective

Smooth acceleration. Aggressive acceleration is the single biggest fuel waster. Accelerate gently and steadily. Imagine there is an egg under the gas pedal.

Maintain steady speed. Use cruise control on the highway. Every speed variation wastes fuel. Steady speed is efficient speed.

Drive at moderate speeds. Most vehicles achieve their best highway fuel economy between fifty and sixty miles per hour. Fuel economy drops rapidly at higher speeds — at seventy-five MPH, you may be using fifteen to twenty percent more fuel than at sixty.

Anticipate traffic. Look ahead and coast to red lights and slowing traffic instead of braking at the last moment. If you can avoid coming to a complete stop, you save the fuel needed to accelerate from zero.

Minimise idling. Idling gets zero miles per gallon. If you are going to be stopped for more than about a minute, turning off the engine saves fuel (many modern vehicles have auto start-stop for this reason).

Maintenance

• Check tire pressure monthly — under-inflation is one of the most common and easily fixed causes of poor fuel economy
• Replace air filters on schedule — a clogged filter restricts airflow
• Use the oil viscosity recommended by your manufacturer — thicker oil creates more friction
• Keep up with scheduled maintenance — a well-tuned engine runs efficiently
• Fix the Check Engine light promptly — it often indicates an issue affecting fuel economy

Vehicle Setup

• Remove roof racks and cargo carriers when not in use
• Close windows at highway speeds (use AC instead — it is more aerodynamic)
• Clear out unnecessary weight from the trunk and back seat
• Use the recommended fuel grade — premium fuel does not improve economy if your engine is designed for regular

Fuel Economy by Vehicle Type

Compact sedans and hatchbacks generally offer the best fuel economy among conventional vehicles. Hybrids in this class can achieve exceptionally high MPG.

Midsize sedans offer a good balance of space and economy. Hybrid versions are increasingly popular and efficient.

Crossovers and SUVs vary widely. Compact crossovers can be nearly as efficient as sedans, while full-size SUVs consume significantly more. Hybrid SUVs are a growing category that offers both utility and economy.

Pickup trucks are the least fuel-efficient conventional vehicles. However, they are essential for many Americans. Choosing a four-cylinder or V6 over a V8, and two-wheel drive over four-wheel drive when appropriate, improves economy.

Hybrids and plug-in hybrids offer the best fuel economy for non-electric vehicles. PHEVs can run on electricity for short commutes and switch to gasoline for longer trips.

Electric vehicles use no gasoline at all, but electricity cost per mile is worth calculating.

Fuel Economy When Buying Used

When shopping for a used car with fuel economy in mind, check the EPA rating for that specific model year and engine, read real-world owner reports (the EPA numbers are optimistic), consider the vehicle's condition — worn engines and transmissions are less efficient, and check whether maintenance has been kept up.

Our reliable used car guide highlights fuel-efficient options. And proper tire selection affects economy too.

Browse fuel-efficient vehicles on Tuble.org. Calculate trip costs with our fuel cost calculator.