Mileage Headed Downhill? (What Causes Bad Fuel Economy?)
November 30, 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.
Commerce Auto Repair
9575 Commerce Rd.
Commerce, Michigan 48382
248.363.3749
Need Service?
More articles from Commerce Auto Repair

Stop Right There!
October 25, 2026
Your vehicles brakes are only as good as its master cylinder. This part is truly is the heart of your braking system, because if it isnt working the way it should, the rest of the brake system cant either. The master cylinder is what takes the pressure you put on the brake pedal and ultimately... More

A Smart Inspection, Peace of Mind Before You Buy
October 23, 2026
With the price of new vehicles these days, you might be thinking about saving some money by buying a used one. But when you go to look at a vehicle, how in the world do you know what youre getting into? A look around the outside and a short test drive likely doesnt give you the confidence that... More

Save Your Tires and Fuel: Why TPMS Is More Than a Warning Lightc
October 11, 2026
You know that little light on your dashboard that looks like a tire? Dont ignore it. Its a lot more than a warning light. Its trying to tell you something that can protect your tires, improve your fuel economy and keep your vehicle traveling safely down the road. Its called TPMS. The abbreviati... More
