How Did My Gas Mileage Get Worse

January 11, 2023


Quite a few things can cause vehicles to get lousy gas mileage. Some are simple to correct, while others may require extensive diagnostic testing. Today we will go over a few of the easier ones.


There are a few products on the market that clean out your engine internals, remove gunk from fuel injectors, and claim to overall smoothen up the engine creating less friction. This is supposed to gain fuel economy.


On newer cars many have GDI. GDI is direct fuel injection into the cylinder head. While it has huge advantages for fuel economy and performance, it does have a downfall. Carbon build-up. Due to the design of this system, large amounts of carbon are left on the valves. This process is heavily sped up by conversion fuel injection.


Under-inflated tires waste gas. Think how hard it is to walk in sand – you must work harder because of the resistance. When your tires don’t have enough air, their rolling resistance is dramatically increased, and it simply takes more gas to get where you’re going. So always check your tire pressure when you gas up. If they’re low – even just a little bit – bring them up to proper pressure. There’s a sticker on the inside of the driver’s door that gives the manufacturer’s recommended tire pressure.

And don’t rely on your tire pressure monitoring system to alert you when you need more air. The TPMS system warns you when the pressure drops twenty percent below recommendations. That’s severely inflated, and you needed more air a long time ago. And if you have a slow leak – get it fixed right away.


If you have a filter that restricts airflow, it will keep the vehicle from breathing and cause poor running conditions. We suggest you check your air filter every six months to ensure it is not clogged. If you live on a dirt road, they may block you every 90 days! So make sure to take a look often!


 Any leak in the fuel or emission system will cause gas vapors to escape. Sometimes it’s as simple as a faulty gas cap; in other situations will need a smoke test to pinpoint the leak. There is many parts to your evap system, so finding the source of a leak is not always easy.



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    So contact us, we are one of the best Chico Auto Repair Shops!

Buddy Rausch

Buddy Rausch

Buddy started his auto career journey at Butte College and started his own auto repair company in 2007. Since then he has worked on countless cars, diagnosing, repairing, and replacing worn, faulty, and broken parts.

After a few years, he moved to a bigger shop to accommodate his growth and to better serve the Chico, CA community. It’s a family-owned & operated business.

Outside of work Buddy enjoys spending time with his family and playing softball is one of his many passions.

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