FuelEcon

Fuel economy for dummies · plain English, zero jargon
PREMIUM · Live Green Zone Active

What are you driving?

Don't know your MPG Imp? Pick your car from the dropdowns — we'll fill it in.

Quick pick your car

No mpg sheet handy? Select make → engine → drivetrain.

📊 Average MPG Imp for this car: -- (EPA estimate)
⚡ Driving an EV? Gas calc doesn't apply — use our EV cost tool.
or enter your own
Source: EIA weekly average

How far are you going?

Slide to set the distance, pick your route, and we'll show what the drive actually costs.

or plan route on map
      ⛽ Fuel needed: 0.00 gal 💰 Trip cost: £0.00
      🌱 Effective MPG Imp: -- mpg
      Tips will appear once you run a trip.

      Frequently Asked Questions

      We take your vehicle's MPG Imp, the total distance of your trip, and the current gas price to work out exactly how many liters you'll need and what they will cost.

      Your car has a base MPG Imp, but things like low tire pressure or driving on back roads instead of the highway make it less efficient. Effective MPG Imp is what your car is actually getting on that specific drive.

      They are very close for most drivers! We use official EPA data for vehicle averages and live gas prices. However, things like heavy cargo, aggressive driving, or very cold weather can change your real results.

      Low tires create more 'rolling resistance,' meaning your engine has to work harder to move the car. Keeping them inflated to the recommended level can save you about 3% to 10% on gas.

      Below 50 mph, windows down is usually better. At highway speeds, the 'drag' from open windows actually costs more gas than running the A/C.

      For most cars, gas mileage drops significantly above 60 mph. Every 5 mph you drive over 60 is like paying an extra £0.20 to £0.30 per gallon.

      Yes. If you are stopped for more than 30 seconds (and not in traffic), it's usually cheaper to turn the engine off and restart it than to let it idle.

      On flat highways, yes. It helps maintain a steady speed, which is much more efficient than constant micro-adjustments with your foot.

      They break the aerodynamic shape of your car. Even an empty roof rack can reduce your MPG Imp by 2% to 5% because of wind resistance.

      The Green Zone is our way of showing you're driving at peak efficiency. When your route and tires are optimized, you're in the Green Zone!

      Yes! Use the 'Save this car' button to keep your vehicle's info in your browser so you don't have to type it in next time.

      We use weekly averages from the U.S. Energy Information Administration (EIA) for the US, and similar official sources for other regions.

      Live widget

      Pin it to your home screen — updates as you drive.

      PWA-ready · installable

      Gas-saving tips

      Small tweaks, real savings — written for humans.

      Freeway over back roads saves 15–25% fuel.
      Check tires monthly → roughly +3% MPG Imp.
      Smooth acceleration + cruise control = free gas.

      How it works

      Planning a road trip or just a long drive to see family? Our Trip Cost Calculator takes the guesswork out of the gas pump. To find your cost, we use a simple three-step formula. First, we take your total trip distance. Second, we look at your car's Miles Per Gallon (MPG Imp) to see how much fuel you'll burn. Finally, we multiply those liters by the current gas price in your area.

      The result is your total estimated fuel cost. But we go a step further! Our tool also calculates your "Effective MPG Imp" based on your driving conditions. If you're driving on back roads with lots of stoplights, your car will be less efficient than on a steady highway. We factor all of this in to give you the most accurate "real world" number possible, helping you budget for your journey with confidence.

      Why it matters

      Gas is often the biggest "hidden cost" of any trip. Whether you're budgeting for a long-awaited vacation or deciding if a 50-mile drive for a "great deal" is actually worth it, knowing the cost upfront is key. According to the EPA (Environmental Protection Agency), aggressive driving—like speeding, rapid acceleration, and rapid braking—can lower your gas mileage by 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic.

      By using this calculator, you can see exactly how much you can save by making small changes to your driving habits. For example, did you know that for every 5 mph you drive over 50 mph, you are essentially paying an extra £0.20 to £0.30 per gallon of gas? Using our tool to plan your route and monitor your efficiency (staying in the "Green Zone") can keep hundreds of dollars in your pocket over the course of a year. It's not just about the math; it's about driving smarter and more sustainably.

      Pro Tip: Keeping your tires properly inflated is one of the easiest ways to save money. The U.S. Department of Energy notes that you can improve your gas mileage by up to 3% by keeping your tires inflated to the proper pressure.

      Frequently Asked Questions

      How do I find my car's real MPG Imp?

      The easiest way is to check your car's dashboard display, but keep in mind that's an average. For the most accurate estimate in our tool, you can look up your car at FuelEconomy.gov to find the "Combined" MPG Imp rating for your specific year and model. If you carry heavy loads or use a roof rack, expect your real-world MPG Imp to be lower than the official rating.

      Is it better to drive with windows down or A/C on?

      It depends on your speed! At speeds under 40 mph, rolling the windows down is usually more efficient. However, at highway speeds (over 55 mph), the "wind drag" created by open windows is actually worse for your MPG Imp than running the air conditioner. Modern climate control systems are very efficient, so when in doubt on the freeway, keep the windows up.

      Does idling really waste that much gas?

      Yes! The U.S. Department of Energy states that idling can burn a quarter to a half-gallon of fuel per hour, depending on engine size and air conditioner use. A good rule of thumb: if you’re going to be stopped for more than 30 seconds (and you aren't in traffic), it's more efficient to turn off the engine and restart it than to let it idle.