MPG Explained: How to Read Fuel Economy

A window sticker shows three MPG figures: city, highway, and combined. Combined is the one to shop on — it blends city and highway (about 55/45) into a single number for comparing cars. City and highway show how the car does in each setting on its own.

MPG — miles per gallon — is simply how far a car travels on one gallon of fuel, so a higher number is better and cheaper. For electric cars the equivalent measure is MPGe (miles per gallon of gasoline-equivalent), which we explain below. All of these come from standardized EPA tests, which is what makes them comparable — and also why your real-world mileage usually lands a little lower.

City MPG is stop-and-go driving; highway MPG is steady higher-speed cruising; combined is the weighted blend. Most gas cars do worse in the city, because braking and accelerating waste energy — but hybrids often do better in the city.

One quirk worth knowing: hybrids frequently post a higher city number than highway, the reverse of a gas car. That's because they recover energy through regenerative braking and run on the electric motor at low speeds — exactly where a gas engine is least efficient. We cover that in the hybrid buying guide.

It depends on the type of vehicle. For a gas car, anything above roughly 30 MPG combined is good and the high-30s is excellent; SUVs and trucks run lower by nature, while hybrids and EVs play in a different league entirely. Compare within a class, not across them.

A 26-MPG SUV and a 33-MPG sedan can both be excellent for their class — judging a truck against a compact only tells you it's a truck. The benchmarks above are EPA combined figures; expect real-world numbers a little lower, as covered below.

MPGe — miles per gallon of gasoline-equivalent — is how the EPA rates electric and plug-in vehicles so they can be compared to gas cars. It converts electricity into the energy in a gallon of gas (33.7 kilowatt-hours = one gallon). Higher MPGe means less energy used per mile.

Use MPG to compare gas cars and MPGe to compare EVs — but don't treat the two as interchangeable dollars, because electricity and gasoline are priced very differently per unit of energy. An EV with a high MPGe is cheap to run on home electricity even when its MPGe "number" looks similar to a thrifty gas car's MPG. For how far an EV goes on a charge — a separate question from efficiency — see the EV range chart.

EPA figures come from controlled lab tests, so real driving almost always lands a bit below them. Cold weather, high speeds, hard acceleration, extra weight or roof racks, low tire pressure, and lots of idling are the main culprits.

None of this means the ratings are wrong — they're consistent, which is what makes them useful for comparison. It just means the sticker is a best-case benchmark. The good news is that the same gentle habits that close the gap (steady speeds, proper tire pressure, combining errands so the engine stays warm) work on any car, and the relative ranking between two models usually holds up in the real world.

Among the gas-only models we track, compact sedans lead — the Honda Civic tops the list at 36 MPG combined. The table ranks the most efficient by EPA combined MPG, each shown in its highest-MPG trim.

This list is gas-only — hybrids and EVs are measured differently, so mixing them in would compare apples to oranges. For the ranking that also weighs price and cost of ownership, see most fuel-efficient gas cars; if you want maximum efficiency overall, a hybrid or electric vehicle will go further on less.