After Service Issue

[hobba]

I have noticed that after I have my routine service performed, (oil change and tire rotation) at my dealer, that my mileage decreases on the MFD display by 5 to 8 MPG. It eventually returns to its normal average of between 45 and 50 MPG. I have a 2005, Pkg 6 with 22,800 miles.

Anyone experience this and what would cause it? Just wondering......

[bbald123]

I'd suspect oil over-fill.

[jdenenberg]

They run your car and the AC while servicing it to check for problems. Since this uses gas while getting no miles, your MPG on that tank will be lower. You should also check the air pressure in your tires after servicing as dealers tend to follow general rules about air pressure and lower psi yield lower MPG.

JeffD

[dogfriend]

Originally Posted by jdenenberg

They run your car and the AC while servicing it to check for problems. Since this uses gas while getting no miles, your MPG on that tank will be lower. You should also check the air pressure in your tires after servicing as dealers tend to follow general rules about air pressure and lower psi yield lower MPG.

JeffD

+1. I took my car in to have the alignment checked just after filling up and resetting the mpg average. The average was 49 mpg when I dropped the car off, when I picked it up it was down to 35 mpg and they only drove it about 7 miles IIRC.

[hobba]

Thanks for the feedback. I did check the oil and it was spot on. I also checked the gas cap and it was seated properly. They did reset the tire pressure, but I increased it when I got home. I am now on my second tank of gas and my mileage is 35 mpg. When I do a manual calculation of mileage, I get 43 MPG.

[pewd]

+2. What Jeff said - no more complex than that - sitting in the bay running without moving - so the computed MPG drops. Normal.

[Michgal007]

My mpg dropped also to ~46 from ~51 I usually get, and I couldn't get it higher. The next tank I got ~ 48 on the highway at 65mph. I was using the A/C (usually I get about 54 mpg at this speed). It was frustrating. I managed to get 51mpg in the following highway tank, but I feel that this is all lower than what I usually get.

I asked for 3.75 quarts of oil and the tire pressure is fine.

[Bear68]

Sad fact is that most techs, being on flat rate, do not drive very gently when test driving cars. The quicker they verify the repair and get the car parked, the quicker they can get started on the next job.

[Bob64]

Ack! My poor baby :/

I'd be heartbroken if my "lifetime average" went down 5-8mpg... since it takes a week or two to get it up by 0.1mpg.

Wonder if I should try making friends with my local hybrid tech and perhaps give them cash over the weekends if they can perform the more-complex maintenance for me.

[hobba]

UPDATED: After a month of driving the car with the MFD showing 35 MPG, I returned to the dealer to have it checked. They said with the use of ethanol in fuel these days, owners can see a 2 - 3 MPG drop in fuel economy. However, they did a fuel consumption test loop of 11 miles and found an average mileage of 54 MPG. Their diagnosis was a reset of the fuel consumption gauge on the MFD. Since then, my mileage indication has returned to normal. Problem solved. Thanks to all who offered advice.