Cars With the Worst Gas Mileage
The car with the worst gas mileage is the passenger car that travels the fewest miles per gallon. Drivers ask which gas guzzlers burn so much fuel, and the useful answer starts with combined mpg, plus city mpg and highway mpg from the same rating method. A lowest gas mileage car can be named only inside a defined US passenger-car group, not across every truck, SUV, and model year at once.
What Counts as the Worst Gas Mileage?
Low gas mileage means a car travels few miles on each gallon of gasoline, so fuel consumption is high for the distance covered. Before calling any vehicle the worst gas mileage car, this discussion is limited to US-market passenger cars from model years 2020 through 2026. Pickup trucks and SUVs stay outside that scope, even when their fuel economy looks poor, because their weight, height, and duty cycle are not comparable to cars. That boundary keeps the lowest-mpg question from mixing unrelated vehicle classes.
Combined mpg is the primary measure here because it blends the city and highway tests into one official figure used for comparing cars. City mpg reflects stop-and-go driving with more idling and lower average speed, while highway mpg reflects steadier cruising. Asking what car has the worst gas mileage without those rules invites mismatched answers, such as mixing an older exotic with a current sedan or treating a truck rating as if it were a car. A consistent population and the same rating method are what make a lowest-mpg claim meaningful.
Cars With Exceptionally Low Published MPG
Among 2020-2026 US passenger cars, the worst car gas mileage usually belongs to high-output sports cars and large-displacement luxury performance models rather than ordinary commuter sedans. Official labels publish city, highway, and combined mpg for one exact configuration, including engine, transmission, and driven wheels. That rating does not automatically apply to every trim of the same nameplate. A complete current label set is required before naming the car with the lowest gas mileage.
Answering what car has the worst gas mileage therefore depends on matching year, market, and configuration, not on a casual ranking of famous nameplates. Two cars can share a badge and still differ by several combined mpg if one uses a larger engine or a different drivetrain. Ranked lists and all-time record claims fall apart when model years, test procedures, or vehicle classes change. The useful move is to read the published city, highway, and combined figures for the specific passenger car in question and treat that configuration as the unit of comparison.
Why These Cars Consume So Much Fuel
Gas guzzlers in this passenger-car group often use large engine displacement so they can meet high power demands under heavy operating load. Displacement alone does not prove poor fuel economy, and horsepower by itself is not a mileage diagnosis, but a big engine working hard spends more fuel per mile. Moving extra vehicle weight takes energy to accelerate that mass, then more energy to overcome tire rolling resistance and aerodynamic drag. Low, wide performance cars can still burn a lot of fuel when they are calibrated to deliver rapid acceleration rather than gentle cruising.
Gearing and drivetrain layout also shape fuel consumption. Short gearing that keeps the engine in a high-load, high-rpm band helps acceleration, yet it raises gallons used on ordinary streets. Extra driven wheels and complex transmissions add mechanical losses between the crankshaft and the pavement. Performance calibration may hold richer mixtures, later upshifts, or more aggressive throttle response, all of which increase fuel use even when the driver is not at full throttle. Those traits show up often in the sports and luxury performance cars with the lowest published combined mpg.
What Low MPG Means for Fuel Use and Ownership
Annual fuel use follows simple arithmetic. In a labeled hypothetical, a driver covering 12,000 miles in a car rated at 12 combined mpg would need 1,000 gallons that year, because miles divided by mpg equals gallons. A car with low gas mileage in that same pattern uses more gallons than a higher-mpg car over the same distance. Owners can estimate fuel spending by multiplying those gallons by the price they actually pay at a local pump, rather than relying on a national average that may not match their town.
Observed mileage often undershoots the label. Short trips, long idling, dense traffic, cold or hot weather, and hard acceleration all raise fuel consumption relative to the highway cycle. City mpg is the closer hint for that kind of use, while highway mpg is more relevant on steady open-road runs. Fuel grade and tank capacity still require checking the specific vehicle; a low combined mpg figure does not by itself prove what octane the engine needs or how many gallons the tank holds. Those details come from the owner's manual for that car.
When Low Gas Mileage Needs Investigation
A car designed as a gas guzzler can still be operating as intended when its fuel economy matches the published combined mpg. Investigation matters when that same car starts using more fuel than its own recent history. Tracking miles and gallons over several fill-ups gives a real-world average, and notes about routes, weather, cargo, and driving style help explain swings. One tank is a weak sample. A pattern across multiple fill-ups is what shows whether the lowest-mpg complaint is the car's normal appetite or a new change.
Safe checks include confirming the tires are at the specified pressure and noticing warning lights, rough running, or a sudden change in how the engine idles. Low mpg by itself cannot identify a failed part; it is a symptom to interpret, not proof that a sensor, injector, or other component has failed. Persistent unexplained fuel-use changes warrant professional diagnosis with the vehicle's own service information. If there is a strong fuel odor or a suspected leak, stop in a safe place and seek assistance rather than probing the fuel system.