This Is Why You Get More MPG On The Highway

The miles per gallon your internal combustion engine (ICE) vehicle can achieve ultimately determines just how heavily you're hit by that old bugaboo, gas prices. They're a reality of driving that we just can't escape (except in the case of EVs, which have issues of range and battery replacement cost instead). As the shrewd drivers among us have surely learned over the years, paying careful attention to fuel mileage can pay dividends in the long run. Typically, you'll notice a higher mpg for highway driving than you do around town. Many factors can reduce your mpg or improve it, but this is common to all types of vehicles.

Broadly speaking, an ICE doesn't like stopping and starting. Efficiency typically takes a hit when in traffic, just as surely as the tempers of commuters do. City driving is a cycle of decelerating, braking, accelerating again, decelerating, and so forth. In a busy urban area, it's rare to get a chance to drive at a regular, uninterrupted pace — this can put wear and tear on your engine as well as drain the gas tank. Highway driving, as regular city commuters will know very well, can be extremely liberating, often allowing freedom to really let rip for long stretches. Running your car at a steady speed also preserves the energy from the car's momentum and maximizes fuel economy.

Let's compare some of the most popular vehicles on American roads today. The 2024 Ford F-150 Lariat boasts fuel economy estimates of 16 mph city and 24 mpg highway, while for the F-150 Raptor this drops to 14 mph city and 18 mpg highway. Toyota's ever-popular RAV4 offers 27 city and 35 highway for 2024. These vehicles are typical in that the highway mileage is consistently higher than city mileage.

According to the U.S. Department of Energy, 55 mph is the optimal fuel efficient speed for a midsize gas vehicle. The mpg at this speed is a broad average of 45, falling to 32 mpg at 75 mph. The most efficient way to operate a vehicle is to gradually accelerate to cruising speed, and hold that speed steadily. 55 mph is a statutory speed limit for rural highways in the U.S., so it follows that most ICEs would be built to perform best at such a pace.

The EPA has the duty of creating fuel economy labels for U.S. vehicles. It has been doing so since 1974, adapting the labels and the information provided on them for over 50 years. Keep in mind that these are only estimates, and results will differ for a particular car based on differences in driving and maintenance habits.

As the U.S. Department of Energy notes, "Aggressive driving ... can lower gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic." 40% may be an extreme case, but it's a huge potential drop in efficiency, and driving with less haste is also safer. Cruise control isn't just about making long journeys less strenuous on the driver, as invaluable as it is for that alone. It will maintain its preset speed more steadily than a human can until there's a need to disengage it. Cruise control can save you up to 20% on fuel, according to Natural Resources Canada.

In a hybrid car or electric vehicle, this phenomenon doesn't apply. For example, the 2025 Prius LE provides an estimated 57 mpg city and 56 highway, which becomes 53 city and 54 highway for the AWD edition of the LE. As for fully electric cars, Tesla's Model 3 offers approximately 145 city and 128 highway mpge. These are very interesting numbers, and there's a good reason why electric vehicles thrive in city conditions. Where some ICE vehicles waste a lot of energy when braking, including through the heat of the process, EVs turn this energy back around to charge their batteries. 

As Natural Resources Canada's 2022 Fuel Consumption Guide puts it, "Electric vehicles also [use] regenerative braking technology to recover energy that would otherwise have been lost." By doing so, they can harness the busy traffic of a city to boost their efficiency advantage even further. Long, clear stretches of highway aren't really very welcome terrain for an EV, though. As CiTTi Magazine put it in July 2023, "BEVs need more electrical current (a measure of power) on highways compared to city streets because the average speed on the highway is higher. Also, their batteries become less efficient at high currents due to energy loss."

As auto technology has improved, it has become easier for different types of vehicles to compensate for their shortcomings. Creeping slowly forward in traffic is nobody's ideal way to travel, but it needn't necessarily be the bane of a gas or diesel engine's existence. Regenerative braking systems are also available for some hybrids. Although though the effect won't be as pronounced as with EVs, anything that returns some energy to that hard-working engine will improve the vehicle's performance and ultimately add up in terms of fuel savings. Aside from providing a smoother application of torque, EV drivetrains generally have more efficient than ICE vehicles. Friction, heat, and noise energy saps a lot of an ICE's efficiency. According to the Environmental Protection Agency, only between 12 and 30% of the energy from a gas-powered engine is transferred to the wheels. For EVs, that rises to 77%.

Hybrids are an interesting case. By their very definition, these vehicles have access to the best of both worlds, harnessing a combination of electric power and traditional fuel according to the current needs of the driver. The disadvantage of this system is that such a vehicle isn't really optimized for either mode, and won't get the sort of electric performance that a dedicated EV does. The range of all-electrics can differ considerably too. Even so, hybrids do tend to perform at their best in the city, because their electric drive systems benefit from regenerative braking capabilities.