Quick question, but my car was just in for service. Last time it was in they clocked roughly 11 miles for the 20k service. This time, I made sure to also note the tank MPG. It was 18.5 when I dropped it off and 17 when I picked it up. I'm sure it was idling a bit and they have the AC cranked, but over 3 miles they put on the vehicle that seems like quite the drop, right?

I'm assuming they may have had some fun in the car, but I wanted a second opinion. The next time it goes in, it'll definitely have a dash cam.

 

seem pretty normall to me......if you warm up your ISF for 5-10 minutes, you will see that drop..

 

I question this as well while I was getting the oil changed last time. Tank MPG before 22.5 and after 18.2 with five miles added. Needless to say, I was suspicious, but couldn't prove it without pictures of the dash. Service agent was like this is normal. I wanted to call BS on it.

 

It would have to idle for quite some time unless the tank was just filled up. When it is a fresh fill, the MPG will drop like a rock when it sits idling even for a short time. The lower the fuel level in the tank, the less the impact of sitting idling. Also the less the impact of a joy ride on a public road. The car gets ~5 mpg under very hard use at the track. AMHIK.