Apparently, BP and Hess are not part it. I also do a lot to Costco gas. I doubt it has anything to do with it. I have another BMW that takes Hess, BP and Costco with no problem and that car is 75,000 miles and counting. I haven't tried any injector cleaner. Those cleaner only cleans up a small amount of dirt besides the car is still under warranty so I rather have BMW to fix it.
This car is near the lease mileage limit and the lease is up in May, so it is only being used sparingly.
After 3 years, I am more than ready to walk away from this car. 1) V8 MPG is too much for me to take, 2) the ride is too floaty for back passenger and 3) trunk is not as useful as I anticipate. I have 2 young kids. Sometimes we need 2 strollers when we go out. 2 strollers in GT gives me no more space in the trunk. I just got the new MB GL diesel. I am very happy with it.
MJ14 535dx - Imperial Blue
MJ10 550 GT - Imperial Blue (retired)
MJ07 530i - Silver Grey (Sold)