Since January '07, I had noticed a big drop-off in the MPG, on my 300C.
After 30K mile service, w/ new plugs, there was no difference. In July,
I went to my favorite vacation spot (same routes, used cruise-control,
used A/C, tires @ 30 lbs.) and got only 23.5 MPG. Previous trips I got
a MPH of 28-32 for an eight hour, mostly interstate trip. I have had
to struggle to get 13.4 around town, when I used to get 15-19 MPH.
Took it to my dealer and there was a TSB bulletin. TSB 1803104REV.A . The NGC Controller was reprogrammed. There has been some improvement in the MPH of my 300C. I have gotten 15.5 MPG around town. 24.0 MPG for an hour trip on interstate. That is an improvement over the 23.5 MPG for an eight hour trip in July. So perhaps the MPG of my C will be as it was last year.
StCassel