Petrol problems!!! HELP!!

So iv noticed lines of what seems to be petrol, its black oily and stinks of fuel!
When iv stopped, switched car off etc etc got out the door, i can smell petrol quite strong.
it seems to be in a long on the drivers side of the car.
any suggestions
much appreciated
Rye
 
Is it only after filling up or all the time? Where is this black oily stuff at on the car?
 
theres a streak on the road where i reverse onto the drive and obviously up my drive to where i park the car. the substance is in lines on the ground not the car.
and no the smells always there everytime i get out the car i can smell petrol but not whilst driving.