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2003 Cadillac DeVille Base 4dr Sedan

2003 Cadillac DeVille
Trim Info:
Front Wheel Drive, 4 Door Sedan, Full Size
18 mpg city / 27 mpg hwy
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November 15, 2012, 8:22 am

Pam L

Question: Gas Mileage

I am averaging 8-9 miles to the gallon in town, and 21 miles on the Highway. Based on the information about my 03 deville, I am supposed to be averaging 18 in town and 27 on the highway. I have fresh oil and a new oil and air filter and use regular gasalione . What seems to be the cause for such low mpg and what can be done to fix it?

November 16, 2012, 9:07 am

Richard W
Expert Mechanic

If your check engine light is not on it will be a little harder to find out why. I would start off by checking your tune up. If the tune up is ok I would check the fuel pressure regulator. They are common for this. They leak fuel into the engine through the vacuum line. Go out the the car take the vacuum line off the fuel pressure regulator. It on the driver side of the engine. But to the left of the throttle body. If you see any fuel it needs to be replaced. If that is ok. You will have to take it into a shop for a better look.

1/1 users found this helpful.

December 5, 2012, 7:23 am

Pam L

Thank you Richard, I will check into it.

0/0 users found this helpful.

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