What each tip is worth to you
Each percentage comes from the U.S. Department of Energy's fueleconomy.gov. The dollar figures use the miles, MPG and price in the calculator, so they change when you change them.
| Tip | Effect on fuel economy | Saves you a year |
|---|---|---|
| Drive calmly on the highway | Aggressive driving costs 15% to 30% | $272 to $544 |
| Drive calmly in stop-and-go traffic | Aggressive driving costs 10% to 40% | $181 to $725 |
| Take off a roof box (highway driving) | A roof box costs 6% to 17% | $109 to $308 |
| Use the recommended motor oil | Improves mileage 1% to 2% | $18 to $36 |
| Remove 100 pounds of extra weight | About 1% per 100 lb | $18 |
| Keep tires at the right pressure | Improves mileage 0.6% on average, up to 3% | $11 to $53 |
The driving-habit rows assume you drive aggressively now and stop. If you already drive smoothly, those savings are already yours. The roof box row assumes all your driving is highway driving with the box on, so scale it down for city miles or for the weeks the box is off.
Three more savings depend on your own habits, so they have their own calculators:
- Idling. fueleconomy.gov says idling can use a quarter to a half gallon an hour. The idling cost calculator shows what your daily idling adds up to.
- The AC. On hot days with short trips, the AC can cut fuel economy by more than 25%. See what the AC costs you.
- Premium in a regular car. AAA's lab testing found no benefit, so every extra cent per gallon is wasted. See what premium costs you each year.
Slow down on the highway
fueleconomy.gov says gas mileage "usually decreases rapidly at speeds above 50 mph." Consumer Reports measured it: in its testing, slowing down by just 10 mph at highway speeds improved fuel economy by as much as 8 mpg. Using cruise control helps you hold a steady speed, and fueleconomy.gov says that in most cases it will save gas.
Consumer Reports also points to SAE International tests in which cars with stop-start systems used 7 to 26 percent less fuel, so it's worth leaving that feature on if your car has it.
Pay less for each gallon
Using less fuel is one half. Paying less for it is the other. The ideas that come up in the top-ranking guides from AARP, CNBC and Experian include:
- Check a gas price app before you fill up
- Buy gas at a warehouse club if you already have a membership
- Use grocery store fuel points and station loyalty programs
- Pay with cash where stations charge less for it
- Use a credit card that pays back more on gas
Two cautions. A cheaper station only saves money if the detour doesn't burn up the difference, and the FAQ below shows the math. And some of the top-ranking lists come from companies that sell financial products, including a credit bureau, so treat card and program recommendations as options rather than must-haves.
What drivers are saying
- Warehouse clubs and grocery fuel points come up constantly, but they depend on where you live. In a Reddit thread on saving fuel, the most common answers were warehouse-club gas stations (Costco, Sam's Club, BJ's), a cash-back card that pays on fuel, and store points that cut cents off each gallon. Commenters mostly said it pays off only if a club or store is close enough to your route, which is the catch with any store-based program (Reddit, r/Frugal, thread from January 2024).
- Driving habits get the most attention from testers. Consumer Reports' own testing puts speed and hard acceleration ahead of most other tips. Hard braking and hard acceleration cut fuel economy by 2 to 3 mpg in its tests.
- Some popular tips don't hold up. Filling up early in the morning, when it's cooler, is one that keeps going around. Consumer Reports tested it and found that "the fuel in our underground tank stayed at a steady 62 degrees F" while the air temperature swung, worth "just a few cents difference on the first gallons pumped" (Consumer Reports, 2008, reprinted by Consumer Watchdog). That's why it isn't in the table above.
We tried to read the full Reddit thread for more detail, but it couldn't be loaded for this page, so the quote above comes from the thread's preview in search results.
Cedrick Reese built this page to answer the question every tip list skips: how much is each one actually worth to you? The percentages come from the Department of Energy's fueleconomy.gov driving and maintenance pages, with Consumer Reports' testing on speed and stop-start systems. The calculator converts them to dollars with your own miles, MPG and price, and the table is checked against the same formulas by hand. Tips without solid testing behind them were left out on purpose. The page is reviewed when fueleconomy.gov updates its figures, and the gas price shown is only an example.
Saving on gas questions
What wastes the most gas in a car?
Aggressive driving. fueleconomy.gov says speeding, rapid acceleration and hard braking can lower gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic. A roof box is next, costing 6% to 17% on the highway and 10% to 25% at Interstate speeds.
Does driving slower save gas?
Yes, on the highway. fueleconomy.gov says gas mileage usually decreases rapidly above 50 mph, and Consumer Reports found that slowing down by 10 mph at highway speeds improved fuel economy by as much as 8 mpg in its tests.
Is it better to keep your gas tank full or half full?
It doesn't change your fuel economy much, but don't let it run low. AAA advises keeping at least a quarter tank, because many fuel pumps sit inside the tank and are cooled by the gasoline, and a nearly empty tank is more likely to pull sediment into the pump.
Is it worth driving to a cheaper gas station?
Only if the detour costs less than you save. Multiply the gallons you're buying by the price difference, then subtract the gas the extra miles use. Saving 20 cents a gallon on 12 gallons is $2.40, and a 6-mile round-trip detour in a 25 MPG car at an example $3.50 a gallon uses about 84 cents of gas, so you'd come out about $1.56 ahead.
Does tire pressure really affect gas mileage?
A little. fueleconomy.gov says keeping tires at the proper pressure improves gas mileage by 0.6% on average and up to 3% in some cases.
More fuel tools
See your full fuel bill with the gas budget calculator, and what a price change does to it with the gas price change calculator. For a single trip, use the fuel cost calculator.
Sources
Last reviewed: October 4, 2026.
- fueleconomy.gov, Driving More Efficiently
- fueleconomy.gov, Keeping Your Vehicle in Shape
- Consumer Reports, Expert Fuel-Saving Tips: How to Get More Miles Per Dollar
- AAA Club Alliance, Why You Should Never Let Your Gas Tank Drop Below a Quarter
- AARP, 10 Ways to Save Money on Gas
- CNBC Select, Best Tools for Saving Money on Gas
- Experian, 19 Ways to Save Money on Gas
- Consumer Reports via Consumer Watchdog, Save on gas with morning fill-ups? Don't bet on it
- Reddit r/Frugal, How do you save the most on fuel?