I went fishing on a river last sunday and I had to drive on a track, grass on either side and grass in the middle. (And getting my tyres extremely mucky with mud and cow-muck) I remember when coming back and hearing a scuffing noice from the bottom of the car. I got out and looked under the car and there was a peice of grass stuck underneath. (Had to get out cus I had to see what route I was going to take to avoid going in to a muddy puddle lol)
When I had my engine oil changed, Kwik-Fit said that the exhuast was going, there was a slight hole in the front pipe......They car does blow a tiny bit. I'm not going to replace it until it gets worse.
THe noise also could be the tyre trim!! ?