Hello,
I recently bought a MCSa with 24k miles. I have noticed that I am getting very poor mileage, approximately 16-17 MPG with moderate driving. I drive my Lotus a lot harder and I get 24-25 MPG with the Lotus. I've checked tire pressures and just got the car realigned. The car is with the dealer and they want me to clean the fuel injectors and the throttle body which doesn't seem like it would make a difference. I've also asked them to check the airfilter. Any suggestions???

 

Oxygen sensors??

 

I would think that defective oxygen sensors would trip a CEL...

 

Dealer service on air filters .... poor to say the least. Get rid of it and go CAI or a K&N or other drop in. I'd also check the brake calipers to make sure they are releasing completely and the wheels spin freely.

 

24K and worse mileage? As above check your air filter. My S's was never replaced by the dealer the first visit as I circled the date and then I put in K & N. Then I found my brother-in-laws MINI with 40K miles had a mouse nest in it. This was 100% dealer serviced for 3 years, had the original filter, same with my sister-in-law's S, dirty filter with 30K miles.

 

I average between 30-32mpg on my '05 MCSa with the mods listed below (this is mixed freeway & city driving). Maybe have the dealer reflash the ECU???

 

Here is what my filter looks like after just 19888 miles. If you were to look straight at it, it would look far worse. Cureently the best milage I have managed to get is about 22mpg, and this is only when I really drive like a grandma (no offense meant to any grandmas out there).



It is getting replaced with an Alta panel in the near future.

 

how the hell do you manage to get such a good mpg?

I get about 23-24 with 70% highway and 30% local.
i'm not driving that hard either.

 

30-32 mpg here also with 60% highway. I generally drive using the paddles upshifting at about 2200 rpm which is just under what the ECU wants to upshift in "D." Also, driving in "D" it seems to take forever for it to go from 5th to 6th (since 6th is so tall - 2000 rpm at 60 mph) so I upshift into 6th as quickly as possible.

 

I get 25 in the worst city conditions (the DC area) and well over 30 on the highway. That is an MCS with the Dinan full meal deal. Are you running premium fuel?

 

I run premium fuel and for the life of me, I can't understand why my mileage is so crappy. The dealer of course, was a total waste of time.

 

oh, BTW, I checked the airfilter (big mistake cuz i couldn't re attach the clamp) and it was clean. I checked the airpressure and that is fine. Alignment is fine. Any other ideas???