I get a very strong smell of petrol inside my golf when driving with the sunroof open. When the roof is closed there is no smell. It would appear that there must be petrol leak; however, there is no sign of a leak anywhere. My fuel consumption is around 35mpg, My previous 2 Gti's managed 38mpg. So it does look like I am losing a small amount of petrol somewhere. Anybody got any thoughts?