The fuel filter is quite well hidden, it is behind the nearside rear wheel arch.
Jack the car up, remove the wheel and remove the arch liner.
You will see the filter just forward of the wheel arch, it is a silver canister held with plastic clips.
It is not uncommon for these filters to split and leak, the leak is hard to notice
apart from the smell of petrol as it fills the undertray before dripping from the car.
Fuel Filter Removal
On each end of the filter is a connector with an orange clip. To disconnect the pipe you
just have to push the orange clip in with your thumb or a screwdriver and pull the pipe.
Picture is from a fortwo but the fuel filter is the same, as is the way it disconnects.
When the pipes have been pulled off you will loose about 100ml of petrol into your sleeves
and all over your shoes. The filter can be pulled out from the plastic holder and replaced.
On restarting the car you will notice a long delay and spluttering as the fuel pump has
to refill the pipes and the fuel filter before it builds up enough pressure for the injectors.
The best way to stop this is to turn the ignition to 1, wait 3 seconds and then turn the key to 0.
Repeat this procedure 3 or 4 times, this allows the fuel pump to reprime the system.
ANT - SP7006
MAHLE - KL72
FRAM - G5857
FRAM - 10230 (Scott B)
MANN - WK612/1
UFI - 3171000
HENGST - H112WK
Halfords - HFF244 (Bernardo)