So thus far, nobody has reported carbon build-up issues.
Model year - 2011
335d or X5d -335d
Mpg - 26.7mpg
Avg speed 33mph?? (will double check)
Brand of fuel - usually BP, unknown cetane
On a scale of 1 to 5 how hard do you drive? 3
Highway/City Mix - 40/60
Carbon build up issue yes or no? -None that I know of
EGR warranty was done, but no other work has been needed. Definitely more reliable (knock wood) compared to my 135i with its fuel pump from hell.
2014 Tesla Model S 85kwh
2011 335d / Deep Sea Blue / Saddle brown / sport / premium
2008 BMW 135i / 6MT
2002 Z06 Corvette