How to Fight High Gas Prices: Simple Ways to Get Better Fuel Mileage

Gas prices on the Front Range have a way of making everyone a fuel economy expert overnight. The good news is that real, measurable MPG gains are not magic. The bad news is that almost nothing sold at the gas station register actually delivers them. Here is what works, backed by the same physics that makes your car move in the first place.

Tire pressure is the single biggest free win

Underinflated tires can cost you 3 percent of your fuel economy per tire. A car with all four tires at 5 PSI low is burning roughly 12 percent more fuel than it needs to. That is real money every fill-up. Find your door-jamb sticker, set pressures cold, and check monthly.

Get the junk out of the trunk

Every 100 pounds of extra weight costs roughly 1 percent of fuel economy. The toolbox you have not used since spring, the camp gear, the bag of road salt that should have come out in March. Take a weekend afternoon to clean out the car. You will feel the difference and the gauge will show it.

Drive like you have an egg under the pedal

Aggressive starts and hard braking can drop fuel economy by 15 to 30 percent in city driving. We are not asking you to crawl off the line. Just smooth out the inputs. Anticipate stoplights. Coast into them instead of throttle-then-brake. Modern engines and transmissions are tuned to reward smooth driving with measurable MPG gains.

Slow down on the highway

Aerodynamic drag rises with the square of speed. The difference between 65 and 75 mph in a typical sedan is 10 to 15 percent fuel economy. On a Denver-to-Fort-Collins round trip, that is real money. You will arrive five minutes later and pay six dollars less. Easy math.

Maintenance you actually need

A few specific service items have direct, measurable MPG impact:

• Fresh oil at the right viscosity: 1 to 2 percent
• Clean engine air filter (only on older cars, modern computers compensate): up to 10 percent on a badly clogged filter
• Working oxygen sensors: up to 40 percent loss when one fails
• Properly inflated, properly aligned tires: 3 to 10 percent
• Functioning thermostat (engine reaching full operating temp): 3 to 5 percent

That last one is sneaky. A thermostat stuck open keeps the engine running cooler than it should, which the computer compensates for by enriching the fuel mixture. You may never see a check engine light. You just see worse mileage.

Fuel grade and the altitude question

Boulder is at 5,400 feet. The 85 octane sold here is roughly equivalent to 87 at sea level for engines designed for regular fuel. Putting premium in a car that asks for regular gives you exactly nothing. If your owner's manual specifies premium, use premium. The knock sensor will retard timing on lower-grade fuel and you will lose power and economy at the same time.

Things that do not work

Fuel additives that promise better mileage, magnets clipped to the fuel line, "tornado" intake spinners, plug-in OBD chips that claim to "unlock" hidden economy. All snake oil. Independent testing has put every one of these through their paces. Save the money for gas.

The route choice nobody mentions

Stop-and-go is the worst thing you can do for fuel economy. If you have a choice between two routes and one keeps you moving steadily, take it even if it is a little longer. A steady 35 mph crushes stop-and-go 25 mph for MPG. This is why backroads to Longmont often beat US-36 plus a stop at every light through Gunbarrel.

When the gauge is lying to you

A sudden 15 to 20 percent MPG drop with no change in driving usually means something is failing. Common culprits: a dragging brake caliper, a partially stuck thermostat, a lazy oxygen sensor, a misfire too small to trigger a light. Bring it in. We will pull live data from the car and find what changed.