Hello, my Smart 450 CDI with 150,000 KM did not pass the exhaust test, otherwise this is a great vehicle and has moved me 20,000 KM in a year without any problems. He smokes relatively strong (black) from the exhaust, could that be a reason? I have not noticed a large oil consumption, rather none at all. The car has power and drives quite normally, only during the acceleration and even when gear is changed, then comes out a thick soot cloud at the back. It is really black and extremely big. What can that be exactly? – Thank you and greetings.