Top 10 Methods to Save Money on Gas and Increase Your MPG

Method One: Adjust Your Driving Speed — Especially on the Highway

Speed is the single most powerful lever for fuel economy improvement, and the physics behind it are unambiguous: aerodynamic drag increases with the square of speed, which means fuel consumption increases dramatically as speeds rise above approximately fifty miles per hour. The EPA estimates that every five miles per hour above fifty miles per hour effectively adds approximately seven to fourteen cents per gallon at current prices, with the effect compounding as speed increases.

The specific numbers: most vehicles achieve their best fuel economy between forty-five and fifty-five miles per hour. Driving at seventy-five miles per hour versus sixty-five miles per hour typically reduces fuel economy by ten to fifteen percent depending on the vehicle's aerodynamic profile. On a vehicle averaging thirty MPG at sixty-five, that is approximately three to four MPG lost — the equivalent of the fuel economy improvement from many mechanical upgrades, simply from driving ten miles per hour faster.

The behavioral implementation: on highway driving, use cruise control to maintain a constant speed rather than the speed drift that occurs with manual throttle control. Set cruise control at or near the posted limit rather than five to ten miles per hour above it. On variable speed limits and open roads where speeds tend to creep up, setting a specific target and using cruise control consistently is the highest single-behavior fuel economy intervention available.

Pro Tip: When using cruise control, disengage it on significant uphill grades and allow the vehicle to slow slightly rather than letting the cruise control open the throttle aggressively to maintain speed uphill. Maintaining constant speed uphill requires a disproportionate fuel expenditure — allowing the vehicle to slow two to four miles per hour on grades and recover speed on the descent uses less fuel overall than maintaining constant speed through the grade.

Method Two: Accelerate Smoothly and Brake Anticipatorily

Aggressive acceleration from stops is the second-largest behavioral fuel economy factor after speed. The fuel consumed in the first ten seconds of acceleration from a stop is disproportionately high because the engine is working at maximum throttle, combustion efficiency is lower at high throttle openings, and in automatic transmissions, the torque converter slip during rapid acceleration wastes energy as heat.

The specific technique: when leaving a stop, apply throttle smoothly and progressively rather than immediately opening to full throttle. The target is reaching your desired speed over approximately ten to fifteen seconds rather than five to seven seconds — the difference in elapsed time is small, the difference in fuel consumption is meaningful. Anticipated stops are equally important: if you see a red light or stopped traffic ahead, releasing the throttle early and coasting to the stop rather than maintaining speed and then braking hard converts the vehicle's kinetic energy into wasted brake heat rather than recovered distance.

Modern fuel-injected vehicles cut fuel delivery entirely during deceleration when the throttle is fully closed and engine RPM is above approximately one thousand — meaning that coasting in gear to a stop uses no fuel at all, while coasting in neutral uses idle fuel to maintain the engine. Coasting in gear rather than in neutral is therefore the more fuel-efficient approach for deceleration on vehicles with fuel injection.

Method Three: Maintain Correct Tire Pressure

Under-inflated tires increase rolling resistance — the energy required to deform the tire contact patch with each revolution — in a direct and measurable way. The Department of Energy estimates that tires under-inflated by ten PSI below specification reduce fuel economy by approximately two to three percent, with the effect compounding across all four tires.

The implementation detail that most people miss: the correct tire pressure for your vehicle is the pressure listed on the door jamb sticker — not the maximum pressure listed on the sidewall of the tire itself. The maximum pressure on the tire sidewall is the maximum the tire can safely contain, not the pressure at which it performs optimally on your specific vehicle. These numbers are typically different by ten to fifteen PSI, and inflating to the tire maximum rather than the door jamb specification over-inflates the tire, reducing the contact patch and potentially producing uneven wear.

Pro Tip: Check tire pressure when the tires are cold — before driving more than one mile. Tires heat up during driving and the air inside expands, producing artificially elevated pressure readings that make under-inflated tires appear properly inflated. Check pressure in the morning before the first trip of the day for the most accurate baseline reading.

Warning: Tire pressure decreases by approximately one PSI for every ten-degree Fahrenheit temperature drop. A tire that was properly inflated in September at seventy degrees will be under-inflated by approximately four to five PSI when temperatures drop to thirty degrees in winter — check and adjust pressure when seasonal temperature changes are significant.

Method Four: Remove Unnecessary Weight

Vehicle fuel economy is directly affected by weight — heavier vehicles require more energy to accelerate and climb grades. The EPA estimates that every one hundred pounds of additional weight reduces fuel economy by approximately one to two percent on average, with a larger effect on stop-and-go driving (where weight directly affects acceleration fuel cost) and a smaller effect on steady-state highway driving.

The practical application: most vehicles accumulate weight in the trunk and cargo area over time — tools, sports equipment, emergency supplies, boxes, and miscellaneous items that were placed in the vehicle for a specific trip and never removed. A meaningful audit of what you are carrying permanently in your vehicle and removing items that are not regularly needed can produce both fuel economy improvement and the specific pleasure of a clean, unencumbered vehicle.

The calculation: one hundred pounds removed from a vehicle averaging thirty MPG produces approximately zero point three to zero point six MPG improvement. Across fifteen thousand miles annually, that is one hundred fifty to three hundred miles of additional range — roughly four to ten gallons of fuel saved, or fifteen to forty dollars annually at current prices. The return is modest per item, but the items are free to remove.

Method Five: Plan Routes and Consolidate Trips

Cold engine operation consumes significantly more fuel than warm engine operation — fuel injection systems deliver richer fuel mixtures during warmup, catalytic converters are less efficient until they reach operating temperature, and engine friction is higher at low oil temperatures. The EPA estimates that short trips — under five miles — consume fuel at substantially worse rates than the vehicle's rated fuel economy because the engine never fully warms up.

The practical implication: consolidating multiple short errands into a single trip that allows the engine to warm up and stay warm between stops is more fuel-efficient than making the same stops across multiple separate trips. A single trip covering four stops uses less total fuel than four individual trips to the same destinations because the warmup fuel cost is incurred once rather than four times.

Route planning that minimizes left turns at busy intersections — reducing idling time waiting for oncoming traffic gaps — is a technique UPS famously implemented across its entire delivery fleet and documented as producing meaningful fuel savings at scale. For individual drivers, the same logic applies: routes that favor right turns and avoid lengthy traffic signal waits at high-traffic intersections reduce idle fuel consumption in aggregate.

Method Six: Use Cruise Control on the Highway

Beyond the speed management benefit described in Method One, cruise control produces a second fuel economy benefit through the elimination of unintentional speed variation. Human throttle control on the highway produces continuous small speed variations — slight acceleration and deceleration as attention wanders, gradient changes, and traffic adjustments — that consume more fuel than the constant-speed operation that cruise control maintains.

The fuel economy improvement from cruise control over manual throttle on highway driving is estimated at seven to fourteen percent in EPA testing, making it one of the highest single-behavior fuel economy interventions on highway driving. The primary caveat: cruise control is less fuel-efficient than expert anticipatory manual driving on roads with significant and predictable grade changes, where a skilled driver can manage speed through grades more efficiently than cruise control's speed-maintenance programming.

Method Seven: Service the Engine Air Filter

A clogged engine air filter restricts airflow into the engine, reducing combustion efficiency and increasing fuel consumption. The historical rule of thumb — that a dirty air filter reduces fuel economy by up to ten percent — was more accurate for older carbureted engines, which compensated for reduced airflow by enriching the fuel mixture automatically. Modern fuel-injected engines with mass airflow sensors are better at compensating for restricted airflow without automatically enriching the mixture, which means the fuel economy impact of a dirty air filter is somewhat lower on modern vehicles — typically two to four percent rather than ten.

Air filter replacement is among the lowest-cost maintenance items — most filters cost fifteen to thirty dollars and take five minutes to replace without tools — making the return on investment positive even at the lower fuel economy improvement estimate.

Method Eight: Maintain the Cooling System and Thermostat

A stuck-open thermostat — one that holds the engine coolant temperature below the normal operating range — prevents the engine from reaching its optimal operating temperature, which reduces fuel combustion efficiency and increases fuel consumption. The engine management system on modern vehicles uses coolant temperature as a primary input for fuel delivery calculations and retains a richer cold-start fuel mixture longer when the thermostat holds temperature below the design setpoint.

Symptoms of a stuck-open thermostat: the temperature gauge never reaches the normal operating range, the heater produces less heat than expected, and fuel economy declines in cold weather more than the ambient temperature would explain. Thermostat replacement is a low-cost repair — typically forty to eighty dollars in parts — that restores normal operating temperature and the fuel economy benefit of proper warmup.

Method Nine: Reduce Aerodynamic Drag

Aerodynamic drag is the dominant fuel consumption factor at highway speeds, and modifications that increase a vehicle's frontal area or surface turbulence meaningfully increase highway fuel consumption. The most common drag-increasing additions that drivers control: roof racks and cargo carriers (particularly empty ones left on after use), truck bed tonneau covers removed (open bed creates significant turbulence at highway speeds), and oversized aftermarket wheels and tires that protrude beyond the wheel well.

Removing empty roof racks when not in use is the highest-return aerodynamic intervention for drivers who use them seasonally — an empty roof rack adds approximately five percent drag at highway speeds on most vehicles. Tonneau covers on pickup trucks improve aerodynamics compared to an open bed and typically produce two to five percent fuel economy improvement on highway driving.

Method Ten: Use the Correct Motor Oil Grade

Using motor oil with a higher viscosity rating than the manufacturer specifies increases internal engine friction and reduces fuel economy by one to two percent. Modern engines are designed to tight tolerances that function optimally with the specified oil viscosity — typically noted in the owner's manual and often on the oil cap or dipstick.

The specific scenario where this matters: shops that default to a single oil viscosity for all vehicles regardless of manufacturer specification, or owners who purchase whatever oil is on sale without checking the specification. A vehicle specifying 0W-20 synthetic oil operated on 5W-30 conventional will see slightly increased friction and slightly reduced fuel economy in addition to potentially reduced protection at cold start.

Fuel Economy Methods Compared

Frequently Asked Questions

Do fuel additives, fuel injector cleaners, and aftermarket devices that claim to improve MPG actually work?

The honest assessment is mixed and product-specific. Fuel system cleaners — products like Techron or Lucas Fuel Treatment — have legitimate use cases for engines with documented carbon deposits or dirty fuel injectors, and can restore fuel economy that has declined due to injector fouling, but they do not improve fuel economy in a well-maintained engine beyond its normal specification. The improvement you see from a fuel system cleaner in a neglected engine is restoration of the factory economy, not improvement beyond it. Aftermarket devices claiming to improve fuel economy — magnets that attach to fuel lines, vortex generators for air intakes, acetone fuel additives, and various electronic modules — have been tested by the EPA and consumer organizations consistently enough to produce a clear consensus: none of them produce measurable fuel economy improvement in controlled testing. The EPA maintains a list of tested aftermarket fuel economy devices with their results — the list contains no devices that produced verified improvement. The mechanisms claimed for these products either violate physics (fuel line magnets) or produce effects too small to measure (most air intake modifications). Save the money and apply it to the genuinely effective interventions in this guide.

Does ethanol content in gasoline — specifically E10 versus E15 — meaningfully affect fuel economy and should I seek out pure gasoline?

Ethanol contains approximately thirty-three percent less energy per gallon than gasoline, which means ethanol-blended fuel produces proportionally lower fuel economy than pure gasoline on a like-for-like basis. The fuel economy impact of E10 (the standard ten percent ethanol blend available at most US gas stations) is approximately three to four percent relative to pure gasoline — a vehicle achieving thirty MPG on pure gasoline would achieve approximately twenty-eight point eight to twenty-nine MPG on E10. E15 (fifteen percent ethanol, increasingly available) produces approximately four to five percent lower fuel economy than pure gasoline. Pure gasoline — available at some stations as "recreation fuel" for marine and small engine use, or at certain stations marketing to fuel economy enthusiasts — produces the highest fuel economy of the three options on energy-content terms. The practical calculation: if the pure gasoline option costs more than approximately five percent above the E10 price, the fuel economy benefit does not offset the price premium and the E10 option is the better value. At price parity or within three to four percent, pure gasoline produces better economy value.

How much do electric seat heaters, air conditioning, and other electrical accessories affect fuel economy?

Electrical accessory load affects fuel economy by increasing the alternator's load on the engine, requiring additional fuel to generate the electrical power consumed. The relative impact varies significantly by accessory. Air conditioning is the highest-load accessory — running the AC compressor reduces fuel economy by five to twenty-five percent depending on ambient temperature (higher impact in hot weather when the compressor runs continuously at maximum capacity), vehicle size, and driving conditions (larger impact in city driving where the AC represents a larger fraction of the total energy budget). Seat heaters, heated mirrors, and rear window defrosters draw significant amperage but operate intermittently and for shorter periods, producing fuel economy impacts of one to three percent when actively running. The practical advice: on highway driving in moderate weather, opening windows produces less aerodynamic drag penalty than running the AC only above approximately forty-five to fifty miles per hour. Below that threshold — in city driving and at lower highway speeds — the AC and open windows produce roughly equivalent fuel economy impacts, and driver comfort should determine the choice.

The ten methods in this guide are arranged from highest to lowest behavioral impact for a reason: the changes that cost nothing and happen immediately — driving at appropriate speeds, accelerating smoothly, maintaining correct tire pressure, removing excess weight — produce the largest percentage improvements for the largest number of drivers, faster than any maintenance intervention can.

The full combination of all ten methods, applied consistently by a driver who was previously operating a neglected vehicle with aggressive habits, can produce fuel economy improvements in the twenty-five to thirty percent range.

The combination of the top three — speed management, smooth driving technique, and correct tire pressure — produces fifteen to twenty percent improvement for most drivers at zero cost and zero maintenance time.

Start with those three.

Implement them today.

Add cruise control discipline on your next highway drive.

Audit your trunk this weekend.

The money you save on fuel this year will compound every year that these habits hold.

They are habits worth holding.