Photo: Julia Avamotive, Pexels
The biggest fuel savings come from how you drive, not what you drive. Accelerate gently, hold a steady speed, look ahead so you brake less, and don’t speed. The federal fuel economy site fueleconomy.gov says aggressive driving (speeding, rapid acceleration and hard braking) can cut gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic. After that, the easy wins are less idling, correct tire pressure and not carrying extra weight. Oregon, Kentucky and Louisiana all cover fuel saving in their driver handbooks, and it can come up on the permit test.
Driving habits that save the most
1. Smooth starts and stops
Avoid rapid starts and sudden stops (Oregon, Kentucky). Kentucky says to pace your driving to traffic and signal timing so you brake and accelerate as little as possible. In practice that means looking well ahead. When a light up ahead turns red, ease off the gas early and coast toward it instead of driving up fast and braking hard.
2. Keep to the speed limit
Fueleconomy.gov says gas mileage usually drops quickly above 50 mph. It estimates that each 5 mph over 50 is like paying about an extra $0.30 per gallon, and that slowing down by 5 to 10 mph can improve fuel economy by 7% to 14%. (Those dollar figures assume gas at $4.28 a gallon, so the real saving depends on local prices.) Oregon’s list starts with “drive steadily and avoid exceeding posted speed limits.”
3. Hold a steady speed
On the highway, cruise control helps you keep a constant speed and in most cases saves gas (fueleconomy.gov, Louisiana). Don’t use it on wet, snowy or icy roads (Oregon).
4. Plan trips and combine errands
Combining errands into one trip is on the Oregon, Kentucky and Louisiana lists. Kentucky also suggests avoiding rush hour where you can, and carpooling, the bus, a bike or walking when they work. In Kentucky’s words, your vehicle is safest and most economical when it’s parked.
Idling: how much it costs, and anti-idling rules
Fueleconomy.gov says idling uses a quarter to a half gallon of fuel per hour, depending on engine size and whether the air conditioning is on. Restarting takes only about 10 seconds’ worth of fuel. Its guidance is that shutting down for longer than a minute saves money. Oregon, Kentucky and Louisiana all say to avoid unnecessary idling.
Some states and cities also limit idling by law. New York City is an example: its Department of Environmental Protection says idling for more than three minutes is illegal, or more than one minute next to a school or park. Rules, exceptions and fines vary a lot between places, so check your state or city before assuming what applies. Never idle in a closed garage. California’s handbook warns that carbon monoxide from the exhaust is deadly and odorless.
Tire pressure, weight and maintenance
| Check | Why it matters |
|---|---|
| Tire pressure | Fueleconomy.gov: under-inflated tires lower mileage by about 0.2% for every 1 psi drop. Correct pressure improves mileage by 0.6% on average and up to 3% in some cases. Louisiana’s guide gives up to 3.3%. Use the pressure on the sticker in the driver’s door jamb or in the owner’s manual. |
| Extra weight | An extra 100 pounds can cut mileage by about 1% (fueleconomy.gov). Empty the trunk of things you don’t need. |
| Roof racks and cargo boxes | A roof cargo box can cut fuel economy by about 2% to 8% in city driving and 6% to 17% on the highway. A rear-mounted carrier costs much less, about 1% to 2% in the city and 1% to 5% on the highway. Remove empty racks (fueleconomy.gov). |
| Motor oil | Using the manufacturer’s recommended grade can improve mileage by 1% to 2% (fueleconomy.gov, Louisiana). |
| Check engine light | Get it checked. It could be something as minor as a loose gas cap (fueleconomy.gov). |
| Air filter | On modern fuel-injected cars, a new filter doesn’t improve fuel economy, though it can help acceleration (fueleconomy.gov). |
Kentucky’s manual links maintenance to clean air. Vehicles are major contributors to ground-level ozone, and emissions rise as a car ages unless it is maintained. Kentucky also says vehicle emissions testing programs in its major population centers flag cars that need repair. Some states run emissions or inspection programs; see your first car: title, registration and inspection.
What a difference it makes
Louisiana’s guide gives an example: a car rated at 30 mpg can fall to as low as 17 mpg with poor eco-driving practices. Small habits, such as easing off early, checking your tires and clearing the trunk, add up.
Quick list for the permit test
- Drive steadily; avoid rapid starts and sudden stops
- Don’t exceed the speed limit
- Avoid unnecessary idling
- Combine errands into one trip
- Keep the vehicle properly maintained, tires inflated
- Remove excess weight
Related: speed limits and the basic speed law, freeway driving for new drivers and towing a trailer, where Kentucky notes driving slower also saves fuel. For licensing in each state, start with learning to drive in the USA.
Sources
- U.S. Department of Energy and EPA, “Gas Mileage Tips: Driving More Efficiently” (fueleconomy.gov)
- U.S. Department of Energy and EPA, “Gas Mileage Tips: Keeping Your Vehicle in Shape” (fueleconomy.gov)
- Oregon DMV, “Oregon Driver Manual: Safe and Responsible Driving, Fuel Saving Techniques” (oregon.gov)
- Kentucky State Police, “Kentucky Driver Manual” (updated July 2026), Motor Vehicles and the Environment (kentuckystatepolice.ky.gov)
- Louisiana Office of Motor Vehicles, “Class D & E Driver’s Guide” (DPSMV 2052, R08/25), fuel economy and tires (public.powerdms.com)
- California DMV, “California Driver’s Handbook, Section 8: Safe Driving (Continued)” (dmv.ca.gov)
- NYC Department of Environmental Protection, “Citizens Air Complaint Program” (nyc.gov)