Back to all

Mileage Headed Downhill? (What Causes Bad Fuel Economy?)

September 21, 2025

Name someone you know who enjoys spending a lot of money on gasoline.  Yeah, me neither. That’s because it costs quite a bit to keep fueling your vehicle.  

One way to save money on gas is to get good fuel economy, and most of today’s vehicles are designed to maximize your mileage.  But you might find you’re filling up more frequently than you used to and are wondering what can cause your fuel economy to tumble.  Here are a few possible reasons your mileage has been headed downhill.

A logical spot to start is in your fuel system.  You may have a faulty fuel injector or an old fuel filter clogged with debris.  Another problem might be oxygen sensors, which measure the air coming into your engine and the emissions going out. An illuminated Check Engine light may be a sign of trouble there. Plus, worn-out spark plugs can reduce your fuel economy. 

Under- inflated, or over-inflated, tires can also be a cause. Make sure they’re all at the same pressure.  When’s the last time you changed your engine air filter? One that’s clogged and dirty can rob you of better fuel economy. Another bandit is a dirty, leaky, or clogged exhaust system, so have it checked out by a pro.

Finally, how you drive can also mean wasted gasoline. Jackrabbit starts and speeding use more fuel than smoother acceleration.  And if you often sit there with your engine idling while you’re waiting somewhere, you’re throwing fuel away.  Just turn the ignition off.

Try out some of these fuel-conserving habits and they’ll pay off for you in the long-run.

Courtesy Auto Repair Plus
967 Bon Air Ave
Tiffin, Ohio 44883
419-443-0797
http://www.courtesyautorepairplus.com

More articles from Courtesy Auto Repair Plus

Courtesy Auto Repair Plus Engine Air Filter Replacement

April 15, 2026

When your experienced Courtesy Auto Repair Plus technician changes your oil, he will also inspect your air filter. You shouldn't need a new air filter at every oil change, but you will need to change it regularly. Heed your technician's auto advice if they tell you to change your air filter.An ... More

Shifty Letters PRNDL (Transmission)

April 14, 2026

You probably figured out those shifty letters. They're what you see on your automatic transmission shifter and stand for Park, Reverse, Neutral, Drive and Low. Your automatic transmission is one of the great automotive inventions; here are some ways you can keep yours working well. Maintain yo... More

What is a TSB? (Technical Service Bulletins)

March 29, 2026

If your vehicle had something in its design or production that the manufacturer had figured out had an unanticipated problem, you'd want to know about it. And you'd want it fixed. There is something that can help drivers with just such a scenario. It's called a Technical Service Bulletin, or TSB.... More