I went out in my S 320 cdi yesterday with my son for lunch the car has been driving like a dream. I kicked the car down to 75 mph and after that it would not go over 2500 revs so I nursed it home it got quite warm with some white smoke comming from under the bonnet.Today I took the car to my local garage 1 mile and a lot of smoke (white) was comming out of the Exhaust they cannot look at it till tomorrow (no Prob) they reckon that it could be the head gasket/s. Any one got any ideas on this as to wether it could be something else? any help would be appreciated. Brian J