Can someone enlighten me as to why the petrol tank breather pipes take such a long route around the rear quarter panels before exiting into the engine bay and then feed to the air intake/filter. can you have the same effect by making a secure hole through the rear firewall and feed straight into the air filter? cheers
Presumably so that the airflow cools the little bulbs and condenses any fuel vapour so it runs back into the tank. Also to loop the breathers higher than the (high-mounted) tank. Probably only important if you live in Africa (or Barnsley). If you took it straight though the firewall, fuel could potentially be siphoned into the air filter, as the tank is higher than the engine.
The bulbs in the tubes are also sneakily arranged so that any petrol that slops into the pipes because you were going round a corner and then somehow gets forced up the pipes by more air / fuel tends to stop in the bulbs and drains back down to the tank instead of spitting out into the air intake. In other words , the stock arrangement is even better than just loops of tubing going up.
VW did not waste money (profit) on anything that wasn't really necessary. I try to bear that in mind when considering options