I had the same problem with my 240D a few years ago. Turned out that the fuel lines were rusted enough that they were allowing fuel to seep out and puddle on the garage floor. I really didn't want to replace the entire lengths of fuel line, so I cut out the bad sections and put in a piece of rubber fuel hose and clamped it in place. It's been holding well for a couple of years. The corrosion occurred where the fuel lines went over the rear trailing arm. The trailing arm had to be dropped for me to reach everything.

Len