You fill up your tank, drive your usual routes, and suddenly realize you already need to stop at the pump again.
If you’re wondering why your gas mileage is getting worse, you’re not alone. Fuel economy can drop for several reasons. Sometimes the explanation is as simple as low tire pressure or a change in your driving routine. Other times, declining MPG can signal that your vehicle needs maintenance.
Fortunately, poor gas mileage doesn’t always mean there’s a major problem. Knowing the common culprits can help you decide what to check first.
What Causes Poor Gas Mileage? Top 6 Reasons
Improperly Inflated Tires
Your tires impact fuel economy more than you might think. When tires aren’t inflated to the vehicle manufacturer’s recommended pressure, they create more rolling resistance, meaning your engine has to work harder to move the car.
Correctly inflated tires save drivers as much as 11 cents per gallon and can extend average tire life by about 4,700 miles. Yet only 19% of consumers inflate their tires properly.
That’s a good reason to make tire pressure one of the first things you check when MPG starts dropping.
Look at the tires themselves, too. Uneven wear, damaged sidewalls, or alignment problems can affect both handling and efficiency. If you’re unsure whether your tires are properly inflated or wearing evenly, call Kwik Kar Denton’s tire rotation experts.
Dirty Air Filters
The filter keeps dirt and debris from entering the engine. Over time, it can get dirty and restricted, especially if you drive in dusty conditions or go a long time between services.
A restricted filter can affect airflow and engine performance. It isn’t always the cause of every MPG problem, but if your air filter is overdue for replacement, book an air filter service appointment.
Your vehicle may also have fuel and cabin air filters with specific replacement intervals. Check your owner’s manual or ask one of our technicians about the recommended service schedule.
Worn Spark Plugs
When spark plugs wear out or get contaminated, your engine may not run as efficiently as it should. You might notice rough running, difficult starting, or reduced performance. In some cases, broken spark plugs can also hurt fuel economy.
Replacing your spark plugs won’t solve every MPG problem. But if your vehicle is due for spark plug service, putting it off isn’t likely to help. A technician can inspect the ignition system and determine whether spark plugs or other parts need repair or replacement.
Fuel and Ignition Problems
If your tires and routine maintenance look good but fuel economy keeps declining, the problem could be related to the fuel or ignition system.
Your engine relies on multiple components working together to deliver and burn fuel efficiently. Problems with fuel injectors, fuel filters, ignition components, or other engine systems affect performance and fuel consumption. You may also notice:
- Hesitation when accelerating
- Rough riding
- Difficulty starting
- Reduced engine power
- Engine misfires
- An illuminated check engine light
Kwik Kar Denton uses state-of-the-art diagnostic services and other inspection methods to identify what’s happening under the hood.
Your Driving Conditions Change Your MPG
Sometimes, there’s nothing mechanically wrong with your car. Your driving conditions strongly influence fuel economy. Frequent short trips, heavy traffic, extended idling, and repeated acceleration and braking all affect how efficiently your vehicle uses fuel.
Highway and city driving can also produce very different MPG results. Weather, air conditioning, extra cargo, and roof racks all affect fuel consumption.
If you’ve recently switched from mostly highway driving to a stop-and-go commute, your lower MPG may be normal. But if you’re driving the same routes under similar conditions and suddenly seeing a significant change, it’s worth investigating.
Overdue Maintenance Can Catch Up With You
Modern vehicles are designed to operate efficiently, but they still require regular service. Perform oil changes, inspections, fluid services, filter replacements, spark plug services, and other maintenance according to your manufacturer’s recommendations.
Skipping maintenance doesn’t cause an immediate problem, which makes it easy to postpone. But as maintenance items become overdue, worn or dirty components can begin affecting performance.
When Should You Have Your Car Checked?
A small change in MPG from one tank to the next isn’t always a cause for concern. Fuel economy can vary based on traffic, weather, driving habits, and other conditions. But a consistent or significant drop should be investigated, especially if other changes accompany it. Consider scheduling an inspection if your:
- MPG has dropped noticeably without a change in driving habits
- Engine is running rough or hesitating
- Check engine light comes on
- Vehicle is harder to start
- Tires are repeatedly losing pressure
- Car isn’t performing normally
A diagnostic inspection determines whether you’re dealing with a maintenance issue, tire problem, fuel or ignition concern, or a change in driving conditions.
Better MPG Starts at Kwik Kar Denton
Poor gas mileage isn’t always a sign that something is seriously wrong. Sometimes the solution is as simple as correcting tire pressure or replacing an overdue filter. Other times, declining MPG can be an early clue that your car needs professional attention.
Noticing poor gas mileage? Kwik Kar Denton can help. From tire inspections and scheduled maintenance to engine diagnostics and tune-ups, our team helps identify what’s affecting your vehicle’s performance and explains what it needs.
Swing by one of our four convenient locations in Denton, Aubrey, Cross Roads, and the North Little Elm Area today. No appointment is needed!
