Fuel Consumption Up? Common Causes to Check

With gas prices in Montreal, every liter counts. If you've noticed your tank empties faster than before, there's probably a technical reason — and often, it's easy to fix.

At the shop, we'll list the most common causes, from simplest to most complex.

Simple Causes to Check First

• Tire pressure: under-inflated tires increase rolling resistance. Check pressure monthly.
• Dirty air filter: a clogged filter reduces airflow to the engine. Replacement: $20–$50.
• Driving habits: hard acceleration, high speed, prolonged idling.
• Excess weight: unnecessary weight in the trunk increases consumption.

Mechanical Causes

• Worn spark plugs: poor combustion wastes fuel. Replacement: $100–$300.
• Faulty oxygen sensor: sends bad data to the engine computer.
• Misaligned alignment: creates extra resistance.
• Clogged injectors: irregular fuel spray.
• Stuck thermostat: engine doesn't reach optimal temperature.
• Stuck brake caliper: creates constant friction.

Key Takeaways

• Check tire pressure and air filter first.
• Worn spark plugs can increase consumption by 10%–30%.
• Alignment and stuck brakes are common mechanical causes.
• An OBD diagnostic can identify electronic issues.
• Regular maintenance is the best prevention.

Frequently Asked Questions

How much should consumption increase in winter?

A 10% to 20% increase is normal in Montreal winter (cold, heating, winter tires).

Does A/C significantly increase consumption?

About 5% to 10%. Comparable to driving with windows down at high speed.

Does regular maintenance improve consumption?

Yes, a well-maintained vehicle can use 10% to 15% less than a neglected one.

Does ethanol in gas affect consumption?

Slightly. Ethanol contains less energy than pure gasoline, so consumption may increase 2% to 3%.

How do I calculate my real consumption?

Fill up, note mileage. At next fill-up, divide liters by kilometers driven and multiply by 100.

Garage Path57 · 7971 15e Avenue, Montréal (QC) H1Z 3N5 · (514) 433-7479