15 Ways to Improve Gas Mileage (Ranked by Impact)
Quick answer: The three highest-impact ways to improve gas mileage are: slow down on the highway (saves 10-25%), maintain correct tire pressure (saves 1-3%), and stop aggressive acceleration (saves 5-10%). Combined, these free changes can improve fuel economy by 15-25%. See all 15 tips below, ranked by MPG impact. Track your improvement with the MPG calculator.
I used to think fuel economy was mostly about the car you drive. After tracking my gas mileage for three years across two vehicles, I found that my driving habits accounted for a 30% swing between my best and worst months in the same truck. The car matters. How you drive it matters more.
These 15 tips are ranked by estimated MPG impact, not by difficulty. I've included the approximate savings and cost for each so you can prioritize the ones that make sense for your situation and skip the ones that don't.
1. Slow Down on the Highway
Estimated savings: 10-25% | Cost: $0
This is the single largest fuel economy improvement available to most drivers, and nobody wants to hear it. Aerodynamic drag increases with the square of your speed — at 75 mph, your engine fights nearly twice the air resistance as at 55 mph.
| Speed | Approximate MPG Loss vs 55 mph | Annual Extra Cost (15K mi/yr) |
|---|---|---|
| 60 mph | -5% | ~$120 |
| 65 mph | -10% | ~$250 |
| 70 mph | -17% | ~$400 |
| 75 mph | -23% | ~$550 |
| 80 mph | -28% | ~$670 |
I'm not suggesting you drive 55 in the left lane. But dropping from 78 to 68 mph — a difference most passengers won't even notice — saves roughly $300/year and adds maybe 5 minutes to a 60-mile commute. On a 500-mile road trip, the time difference between 75 and 65 mph is about 45 minutes. Whether that's worth $30-40 in gas is your call.
2. Fix Your Acceleration Habits
Estimated savings: 5-10% | Cost: $0
Jackrabbit starts from every red light are the second biggest fuel waster. Rapid acceleration dumps extra fuel into the engine to build power you don't need. Smooth, moderate acceleration to your target speed uses 20-30% less fuel than flooring it.
The technique: accelerate at about 60-70% throttle (enough to keep up with traffic, not enough to push you back in the seat) and reach your target speed within 15-20 seconds. You don't need to hypermile or annoy people behind you — just don't treat every green light like a drag strip.
Similarly, if you see a red light ahead, coast instead of maintaining speed and braking at the last second. Coasting uses zero fuel in most modern cars (fuel cut on deceleration), while maintaining speed up to the line wastes gas you immediately convert to brake heat.
3. Check and Maintain Tire Pressure
Estimated savings: 1-3% (up to 6% if severely underinflated) | Cost: $0-15 for a gauge
Under-inflated tires increase rolling resistance. Every PSI below the recommended pressure costs about 0.2% of your fuel economy. Tires naturally lose 1-2 PSI per month, and cold weather drops pressure by about 1 PSI per 10F temperature change.
Check your tire pressure monthly and every time the temperature drops significantly. The recommended pressure is on the sticker inside the driver's door jamb — not on the tire sidewall (that's the maximum, not the optimal).
| Pressure Status | MPG Impact | Extra Annual Cost |
|---|---|---|
| At recommended PSI | Baseline | $0 |
| 3 PSI low (all tires) | -1.5% | ~$40 |
| 6 PSI low (all tires) | -3% | ~$75 |
| 10 PSI low (all tires) | -5% | ~$125 |
4. Remove Unnecessary Weight
Estimated savings: 1-2% per 100 lbs removed | Cost: $0
Every 100 pounds of extra weight reduces fuel economy by approximately 1-2%. This matters more for smaller vehicles (higher percentage of total weight) and in city driving (more acceleration events).
Common culprits: tool boxes, golf clubs, strollers, cases of water, car seats for kids who haven't been in the car in months, that bag of sand from last winter. I pulled 160 pounds of "might need it" out of my truck bed and gained a measurable 0.8 MPG over the next five tanks.
Roof racks and cargo boxes are worse than trunk weight because they also increase aerodynamic drag. An empty roof rack costs 2-5% fuel economy at highway speed. A loaded cargo box costs 10-25%. Remove them when not in use.
5. Use Cruise Control on the Highway
Estimated savings: 3-7% | Cost: $0 (if equipped)
Cruise control maintains a constant speed, which is more efficient than the human tendency to gradually speed up and slow down. Most people drift between 65 and 75 on a long highway drive without realizing it — those fluctuations waste fuel.
The exception is hilly terrain. Cruise control fights hills by adding throttle to maintain exact speed on inclines, which burns more fuel than a skilled driver who allows speed to drop slightly on uphills and recover on downhills. On rolling hills, manual driving with gentle speed variation beats cruise control.
Adaptive cruise control (ACC) with a smooth following distance setting is even better than standard cruise in traffic because it anticipates speed changes and adjusts gradually rather than braking hard.
6. Plan and Combine Trips
Estimated savings: 5-15% | Cost: $0
A cold engine uses 20-40% more fuel for the first 3-5 miles of driving. Multiple short trips with cold starts consume significantly more fuel than one combined trip covering the same total distance with a warm engine.
If you typically make three separate trips — grocery store, dry cleaner, gym — combining them into one loop eliminates two cold starts. Over a week, that's 6 cold starts saved. Over a year, it adds up to 30-50 gallons for a typical suburban driver.
Route planning also matters. Right turns are more fuel-efficient than left turns (less idling at intersections waiting for oncoming traffic). UPS famously saves 10 million gallons annually by routing trucks to minimize left turns.
7. Use the Recommended Oil Grade
Estimated savings: 1-2% | Cost: $0 (you're buying oil anyway)
Using 10W-40 when your engine calls for 0W-20 increases internal friction significantly. Modern engines are designed around thinner oils for a reason — they flow faster at startup (reducing cold-start friction losses) and maintain proper lubrication at operating temperature with less drag.
The recommended grade is in your owner's manual. Using thicker oil "for protection" is a myth from the 1970s that costs you fuel and may actually cause more wear in engines designed for thin oils because it doesn't reach tight clearances quickly enough at startup.
8. Keep Up With Engine Maintenance
Estimated savings: 2-4% | Cost: Varies
A well-maintained engine burns fuel efficiently. Neglected maintenance creates a slow, invisible drain on fuel economy:
| Maintenance Item | MPG Impact if Neglected | Typical Cost |
|---|---|---|
| Dirty air filter | -2 to -6% (older carbureted cars), -0 to -1% (fuel-injected) | $15-25 |
| Worn spark plugs | -2 to -4% | $40-100 |
| Failed O2 sensor | -5 to -15% | $100-300 |
| Low coolant / overheating | -5 to -10% | $10-20 (coolant) |
| Dragging brakes | -5 to -10% | $150-300 (brake service) |
| Clogged fuel injectors | -2 to -5% | $100-200 (cleaning) |
9. Avoid Excessive Idling
Estimated savings: 1-5% (varies by driving pattern) | Cost: $0
Idling gets 0 MPG. A modern fuel-injected engine burns 0.15-0.50 gallons per hour at idle depending on engine size. If you idle for 15 minutes a day (warming up, drive-throughs, waiting for pickups), that's about 40-130 gallons per year wasted.
The old rule of "it takes more gas to restart than to idle" hasn't been true since carburetors disappeared. With fuel injection, restarting uses the equivalent of 7-10 seconds of idling. If you'll be stopped for more than 30 seconds, turning off the engine saves fuel. Vehicles with auto stop-start do this automatically.
Warming up a modern engine for more than 30-60 seconds is unnecessary and wasteful. Drive gently for the first few minutes instead — the engine warms up faster under light load than sitting in the driveway.
10. Close Windows at Highway Speed
Estimated savings: 1-3% at highway speed | Cost: $0
Open windows create turbulence inside the cabin and increase aerodynamic drag. At speeds above 40-45 mph, the fuel penalty from open windows exceeds the fuel cost of running the AC.
Below 40 mph, windows down beats AC. Above 45 mph, AC beats windows down. In the 40-45 range, it's a wash. The exact crossover depends on your vehicle's aerodynamics — a sleek sedan's windows create less drag than a boxy truck's.
11. Use the Right Fuel Grade
Estimated savings: 0-3% + cost savings | Cost: Saves $0.30-0.60/gallon
If your car requires regular (87 octane), using premium (91-93) does nothing. Zero benefit. Premium fuel doesn't burn "cleaner" or "better" in an engine designed for regular — it simply resists pre-detonation at higher compression ratios, which your engine doesn't have.
If your car recommends but doesn't require premium, running regular saves $0.30-0.60 per gallon with a potential 1-3% loss in power and efficiency. The engine's knock sensor adjusts timing to accommodate the lower octane. Whether the small efficiency loss offsets the price savings depends on the gap — at $0.50/gallon difference, regular almost always wins.
If your car requires premium (high-compression or turbocharged engines), use it. Running regular causes the engine to pull timing, reducing power and potentially increasing fuel consumption by 3-5%, which often costs more than the premium surcharge.
12. Park in the Shade
Estimated savings: 1-2% in hot weather | Cost: $0
A car parked in direct sun on a 90F day reaches 140-170F interior temperature. When you start it, the AC runs at maximum for 5-10 minutes to cool down, which puts a significant load on the engine. Parking in shade keeps the interior 20-30F cooler and reduces the AC's initial workload.
If no shade is available, a windshield reflector ($10-15) reduces interior temperature by 15-20F. Cracking the windows slightly helps too, but only if you're in a safe area.
13. Avoid Short Trips When Possible
Estimated savings: 3-8% (if you eliminate several short trips per week) | Cost: $0
The first 3-5 miles of any trip are the least fuel-efficient because the engine, transmission, and catalytic converter haven't reached operating temperature. A 2-mile round trip to the store might get 30-40% worse fuel economy than the same car on a warmed-up highway cruise.
Can you walk or bike for errands under a mile? Can you batch your short trips into one longer trip? This is more about trip elimination than driving technique.
14. Keep Your Gas Cap Sealed
Estimated savings: 0-1% | Cost: $0-15 for a replacement cap
A loose, cracked, or missing gas cap allows fuel vapor to escape from the tank. Modern evaporative emissions systems recirculate these vapors back into the engine to be burned, but a leaking cap lets them escape into the atmosphere instead. This won't show up as a dramatic MPG change, but it triggers a check engine light on most vehicles.
If your gas cap doesn't click when tightened, replace it. A universal cap is $8-15 and takes 10 seconds to install.
15. Consider Fuel-Efficient Tires
Estimated savings: 2-4% | Cost: $0 extra when replacing worn tires
Low rolling resistance (LRR) tires are designed to flex less, which reduces the energy lost as heat with each rotation. When your current tires wear out, choosing an LRR replacement can improve fuel economy by 2-4% over standard tires of the same size.
The trade-off is usually slightly less wet traction and shorter tread life, though the gap has narrowed significantly in the last decade. Modern LRR tires from Michelin, Continental, and Bridgestone perform within 5-10% of standard tires in wet braking while delivering measurable fuel savings.
Don't buy new tires just for fuel economy — wait until you need replacements and factor LRR into your decision. The fuel savings on a 50,000-mile tire set are typically $200-400, which often covers the price difference if there is one.
Total Impact: What Can You Realistically Save?
Nobody implements all 15 tips perfectly. Here's a realistic scenario for a typical driver who picks the easy wins:
| Change | MPG Improvement | Annual Savings |
|---|---|---|
| Drop highway speed from 75 to 68 | +12% | $290 |
| Fix tire pressure (was 5 PSI low) | +2.5% | $60 |
| Smoother acceleration | +5% | $120 |
| Remove 100 lbs from trunk/bed | +1.5% | $36 |
| Use cruise control | +3% | $72 |
| Combine weekly errands | +3% | $72 |
| Total | ~20% | ~$650/year |
Use the fuel cost calculator to plug in your own numbers and see what each change is worth for your specific driving pattern and gas prices.
FAQ
Does premium gas improve fuel economy?
Only if your engine is designed for it. High-compression and turbocharged engines that require premium will run less efficiently on regular because the ECU retards ignition timing to prevent knock. For engines designed for regular (87 octane), premium offers no measurable benefit to fuel economy, power, or engine longevity. You're paying $0.30-0.60 more per gallon for nothing.
Do fuel additives work?
Most don't. The FTC has taken action against several fuel additive companies for making unsubstantiated mileage claims. The exception is top-tier gasoline detergent additives (like Techron) which can help clean clogged fuel injectors — but only if yours are actually dirty. A can every 15,000 miles is reasonable preventive maintenance. Anything claiming to "boost MPG by 20%" is snake oil.
Is it better to fill up in the morning when gas is cooler?
Theoretically, cooler gas is denser so you get more energy per gallon. In practice, underground storage tanks maintain a relatively constant temperature year-round, so the temperature difference between morning and afternoon fill-ups is negligible — maybe 0.1% more fuel. Not worth changing your routine.
Does driving with the tailgate down improve truck MPG?
No. MythBusters tested this, and multiple aerodynamic studies confirm it. A closed tailgate creates a stable air bubble in the bed that deflects airflow over the truck smoothly. An open tailgate (or removed tailgate) disrupts that bubble, increasing drag. A tonneau cover is the best option — it creates a smooth surface that reduces bed turbulence and improves highway MPG by 1-3%.
How much does AC really cost in fuel?
AC typically reduces MPG by 3-10% depending on outside temperature, system efficiency, and vehicle size. On a 95F day, a small car's AC might consume 3-5 HP continuously, while a large SUV's might consume 5-8 HP. At highway speed, that's 3-5% of the engine's output going to cooling. In city driving with frequent stops, the percentage is higher because the engine is producing less total power.
Next Steps
- Measure your current baseline MPG with the MPG calculator before making changes — you can't improve what you don't measure.
- Calculate exactly what your commute costs in fuel with the fuel cost calculator.
- Learn the exact formula and tracking method in our how to calculate MPG guide.