“Fuel-efficient” depends on where you drive. A car that is excellent in city traffic can be ordinary at 75 mph, and winter can cut the numbers of almost any car. So the best choice starts with a look at your own mix of driving.
In the city: hybrids lead
Stop-and-go traffic is where conventional engines waste the most fuel, and where hybrids recover energy every time you brake. Full hybrids such as the Toyota Prius, Corolla Hybrid and Camry Hybrid, the Honda Accord Hybrid and the Hyundai Elantra Hybrid often match or beat their highway rating in town. Electric cars go further still: they use no fuel at all and are very efficient at low speed, if you can charge at home or work.
Small size helps too. A compact hatchback has less weight to move from every traffic light, and it is easier to park, which is another reason it suits urban drivers; see our guide to cars for city driving.
On the highway: aerodynamics and steady speed
At highway speed, air resistance becomes the main load. Low, smooth sedans usually do better here than tall SUVs of similar weight, and diesel engines (where still sold) and efficient hybrids keep good numbers on long runs. Speed matters more than most people expect: dropping from 75 to 65 mph often saves more fuel than switching models. For more on that, read how to improve your fuel economy.
All year round
Cold weather increases fuel use for every car. The engine takes longer to warm up, winter fuel blends contain slightly less energy, tires lose pressure, and heaters and defrosters draw power. The US Department of Energy notes that city fuel economy can drop noticeably in cold weather and short trips, and electric cars lose range too, particularly without a heat pump.
If you drive a lot in winter, a hybrid tends to keep its advantage, and a plug-in hybrid gives you electric commuting with a gas engine as backup for long, cold trips.
How to compare models
Use the official figures as a ranking, not a promise. The US site fueleconomy.gov lists city, highway and combined MPG for every model since 1984, with an estimated annual fuel cost and, for many cars, mileage reported by real owners. That last number is often the most honest.
When two models are close, look at the version you would actually buy. All-wheel drive, bigger wheels and sport trims all cost a few MPG. And remember that a cheap but thirsty car may still cost less overall than an expensive efficient one if you drive little; the break-even point depends on your annual mileage. Our article on the benefits of hybrid cars runs through that calculation, and sustainable car choices look at the environmental side.
