I was told by a tech that these cars are not designed for freeways in north america but for the those found in Germany. He said that these cars need to be drive fast and to hard to burn off the carbon on the intake manifold. He explaind to me that next time i am driving on the highway to slip the car from drive to 3rd and let the rpms come 4000 rmps couple for about ten mins or so to burn off all that carbon. But what i did last week is I gave the car to my cousin, who is a police officer and he drove the car hard for an hour(we did get pulled over at 187kms..no ticket. It did helped, there was more power and less smoke comming from the tail end, but a small oil leak did show up....a hundred doller fix...more power and a hell of a ride i think it was well worth it.