I have a P reg Vauxhall Astra 1.6 and just recently the exhaust leaves a black mark on the ground. I do notice that this only happens when the car hasn't been used for a few hours, but the thing is that the exhaust isnt letting out black smoke to look at only where it has been coming out and going onto the ground. I notice the car is jerky sometimes when it is driven. The engine management light now also comes on and goes off from time to time.
Does anyone know what might be causing this, and does it sound like a serious or expensive problem?
Thanks in advance