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Q: What is causing the massive loss in mpg?

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I own a 2010 Chevy Cobalt, 2.2l Ecotec 5 speed manual. Bought it used with 73k miles on it. I've been driving highway since Monday on a full tank of gas, reset my mpg average. The car is rated 37 highway, and my on board dash mpg average is at 31 mpg. The car is running fine, a tune up might be due but that couldn't possible cause a 5+ mpg loss. Any suggestions? Ran my code reader and nothing coming up or stored, car. Seems to be running just fine. No issues anywhere

My car has 73000 miles.
My car has a manual transmission.

A: Hi, thanks for writing in. A tune up can de...

Hi, thanks for writing in. A tune up can definitely cost several miles per gallon, depending on how badly it needs the tune up. There are several factors that go into fuel mileage: how much actual city driving there is, highway speed has a huge effect, what rpm you shift at, and even the quality of the gasoline being used. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this gas mileage issue for you, and make or suggest any repairs as needed

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