I live in Europe and have a E91 330d. Here we also have carbon buildup in the engines.
Well, maybe not in the engine itself, but in the intake manifold. Partly because of the Carbon build up the problem with the swirl flaps was present on the first generations of the M57 engine producing 204hp here in europe. My first E46 330d was the first generation without the swirl flaps. On that model the turbo was known to last for approx. 250.000km and then had to be changed. Mine lasted 302.000km.
On my E91 I have resently had to get the inlet manifold changed as a precaution to the swirlflaps falling off and getting into the engine because of carbon buildup around the flaps. I saw my manifold and the carbon inside it was not that bad.
I have seen and heard of others who mostly drive in the city and drive short trips where the engine actually brakes down and has to be changed after only 30.000km. That was not BMW's though.
Injectors does not last more that about 200.000km, sometimes less.
Properbly because I drive a lot of highway in my approx 50-55.000km a year. And almost every time i'm there I run at everything between 130km/h to 200-240km/h depending on the traffic and who I meet on the way that wanna play ;-)
In that perspective I agree....floor it and the carbon buildup will be less than it will be if you just drive to the local backery every sunday morning and back.....
'06 E91 330dA Sparkling Graphite|19" AvantGarde M359 Satin Black|335i brakes|Bilstein B16 IRC|Powerflex|GroundControl|Wagner|Ecotune|Turbo Dynamics|Zimmermann