Over time, even the most fuel-efficient vehicles can start losing gas mileage. Many factors may cause this to happen, but fortunately, it’s an issue that’s often preventable with regular auto maintenance and safer driving practices. Maintaining good fuel economy is not only important for saving money and cutting emissions but also ensuring your car is running at peak performance. Here are some of the top reasons gas mileage decreases.

What Causes Reduced Fuel Efficiency?

1. Poor Driving Habits

Being an aggressive driver can lower gas mileage by up to 30% on the highway and 40% on city streets. Heavy braking, quick acceleration, and speeding consume more gas than necessary because they put excessive wear on the engine. To help conserve fuel, don’t drive over the speed limit, ease into your braking and accelerations, avoid idling when parked, and refrain from revving the engine.

2. Bad Motor Oil                                                                     

auto maintenance

Frequent oil changes are a vital part of any auto maintenance schedule. Skipping these causes your car’s engine to work harder once the old oil begins to break down, burning more gas per mile. Using the wrong kind of motor oil for your vehicle can also lead to engine problems, like overheating. Get your oil changed at the recommended intervals, replacing it with the type of oil suggested in your owner’s manual. 

3. Improper Tire Pressure 

Over or underinflated tires are less efficient because the incorrect air pressure will require more energy to move the vehicle. In turn, this increases fuel use. Improper inflation can also cause the wheels to go out of alignment, which puts them under excessive strain and decreases fuel economy as well. Check your tire pressure at least once a month and adjust it accordingly. Typically, an alignment should be performed one or two times a year.

4. Clogged or Faulty Fuel Injector

A fuel injector is designed to deliver gas to the car’s engine; if it’s not working appropriately, your vehicle won’t achieve optimal gas mileage. Fuel injectors may become clogged from carbon deposits that accumulate after driving thousands of miles. They can also get damaged and leak. Either problem will prevent enough fuel from getting to the engine. If you experience rough idling, engine misfires, or a strong smell of gas, a mechanic may need to clean or replace the component.


If you’ve noticed your vehicle getting less gas mileage than normal, visit Sundance Auto Service & Machine Shop in Phoenix, AZ. They offer a broad range of auto maintenance and repair solutions that will help maximize your car’s fuel efficiency. With more than 75 years of combined experience, these skilled mechanics provide high-quality workmanship at honest prices. Call (602) 340-0966 to discuss your needs, or learn more about their services online