I have an intermittent petrol leak on a 1996 A4 2.6 V6, from underneath (by the filter, drivers side under rear door). In this hot weather the filter / pipes are dry when I get the car jacked up so I cannot see any leak, even with the car running. Can do a few trips with no leak evident, then start up and it leaks. Stop engine get the jack out, all evaporated, no sign of leak. The pipes look fine, the clips on the hose are tight. I have lain under the car with engine running, dry as a bone.......but when it does leak it is a steady stream of petrol. Any ideas welcome.