Why Is My Car Using Too Much Gas?
- Tyler Ellis
- Oct 5
- 3 min read
If your MPG has dropped or you’re filling up more often, you’re not alone. Many drivers ask, “Why Is My Car Using Too Much Gas?” and the answer usually comes down to a few fixable issues. Catching them early can restore fuel economy, performance, and reliability.
At Round Rock Auto Center, we diagnose the real cause of poor MPG and fix it right so you stop paying extra at the pump.
Common Causes of Poor Fuel Economy
Fuel economy suffers whenever the engine, tires, or aerodynamics make your car work harder than it should. The most common culprits include:
Underinflated or uneven tires – Just a few PSI low can cut MPG and wear tires faster.
Wheel alignment out of spec – Drag from misalignment wastes fuel and causes pulling/uneven tread wear.
Clogged air filter or dirty MAF sensor – Restricts airflow or skews readings, forcing a rich fuel mix.
Aging spark plugs or ignition coils – Misfires and incomplete combustion burn more fuel.
Stuck-open thermostat – Engine runs too cool, enrichment lasts longer, MPG drops.
Failing oxygen (O₂) sensors – Bad feedback to the ECU causes rich mixture and poor MPG.
Dragging brakes – Seized caliper pins or stuck parking brake create constant resistance.
Short-trip driving – Engine never reaches efficient temps; start-up enrichment kills mileage.
Excess weight & roof racks – Added mass and wind resistance raise fuel consumption.
Low-quality fuel or wrong octane – Can reduce efficiency or cause knock-retard.
EVAP/gas cap issues – While often emissions-related, a faulty cap can contribute to running inefficiencies.
How to Fix It (Step-by-Step)
You can knock out several MPG killers quickly. If you’re still wondering “Why Is My Car Using Too Much Gas?” after these, a professional diagnostic will pinpoint the rest.
Set tire pressures to the door-jamb spec and inspect tread wear patterns.
Replace the engine air filter if dirty; clean the MAF with sensor-safe cleaner if needed.
Check for brake drag (hot wheel, burning smell) and have sticking calipers serviced.
Service ignition – Inspect/replace spark plugs at the recommended interval; test coils if misfire codes appear.
Verify coolant temps – A thermostat stuck open keeps the engine cold and wastes fuel.
Scan for codes & trims – O₂ sensor, MAF, or fuel trim faults point straight to mixture problems.
Lighten the load & remove racks when not in use; avoid long idling and combine short trips.
Use quality fuel and the manufacturer’s recommended octane.
For a full workup, schedule with Round Rock Auto Center. We’ll road test, scan live data, measure fuel trims, check alignment, and inspect brakes to find the exact cause.
Why Act Now
Delaying a fuel-economy fix costs more than gas money:
Catalytic converter protection – Rich running overheats and damages the cat.
Tire & brake life – Misalignment and drag chew through tires and pads.
Performance & safety – Hesitation and misfires can affect drivability and passing power.
Budget & environment – Extra fuel burn hits your wallet and emissions.
If you keep asking “Why Is My Car Using Too Much Gas?”, that’s your cue to get a proper diagnosis before small inefficiencies snowball into major repairs.
Get Your MPG Back
Stop guessing and start saving. If you’re wondering “Why Is My Car Using Too Much Gas?”, our ASE-certified techs will pinpoint the cause and restore your efficiency. Contact Round Rock Auto Center to book a fuel-economy diagnostic and get back to fewer stops at the pump.
Related Posts:
Comments