Hi everybody!
So here is my problem. I came back from my indy shop just now, to check my car for faults. He found 3 hard ones that would not clear. KBM control module fault causing overvoltage. Redouts were between 13,9V and 14,6V. Some ARS fault but we performed test and was working fine. There was also CAN communication fault that has not cleared. I have no idea if any of these would impact fuel consumption, but might be mistaken. I will replace that KBM was quoted 295 plus tax for the part plus labor. I have no idea about that can communication thing. What bothers me the most is lost mpgs. I was averaging 20. It has dropped to 16 - 17 mpg. My friend has X5 with same N62 engine and takes same route to work. He averages 18,5mpg. Any advice would be greatly appreciated! The goy also offered check my cars software and update it for $200 including engine transmition software as wel as progman. Do you think it is reasonable? Thanks!

 

how were you figuring the mileage? by the on board computer? or by mileage divided by gallons pumped in?

 

I have divided miles by the gallons pumped in. I drive to work early mornings 5am and come back late. It is at about 45 - 50 mph. Usually cruise controll is in use ( I drive for a living so I am lazy) my onboard computer reading differs by one mpg. As I mentioned before friend with x5 gets better mpg than me using the same route. I own a car for 4,5 years now. I know something is up...

 

check tire pressures.
try different gas station.
clean maf sensor.

maybe the overvoltage code is your problem. the alternator is working harder and putting more of a drag on the engine. is your battery ok? how old is it?

 

I will see what it will be after I replace that module. Tire pressure is ok. I check it weekly as well as oil level. I would understand 1 or 2 mpgs but 4 and no faults in dme or anywhere else is just strange...