Mileage Headed Downhill? (What Causes Bad Fuel Economy?)
December 28, 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.
Auto Lab Troy
2790 West Maple Rd.
Troy, Michigan 48084
(248) 643-7690
Need Service?
More articles from Auto Lab Troy
Cabin Air Filter and Engine Air Filter: What?s the Difference?
March 8, 2026
You may have heard someone say they just got the air filter replaced in their vehicle. But did you know your vehicle has two different major air filters and they both perform quite differentbut very importantduties? Todays vehicles have a cabin air filter, and an engine air filter. The engine a... More
Why is My Brake Pedal Hard to Push?
March 1, 2026
When you push on your brake pedal, you should find your vehicle easy to stop. But at some point, you might notice stopping takes much more pressure on the pedal than it used to. When it gets to that point it becomes a safety issue, and you should bring your vehicle in so we can track down whats... More
Power Steering Pump Replacement
February 22, 2026
When youre driving and you hear a squeal or groan when you turn, it may be a sign your power steering pump is on its last legs. The same is true if you feel your steering is slipping or doesnt respond to your hands like it used to. Precise, responsive steering is, of course, important when it ... More