niceone didnt know that! is it safe? mite give this a try...
Don't do it in a petrol car, only a diesel. Petrol expands way more than diesel when it gets gets heated up (by being pumped to the engine and back for example) and it'll overflow. It's for this reason that the vent system was designed, to stop petrol cars being overfilled and leaking. Diesel is fine though.
Phil. When you fill up, the tank vent system holds an air bubble inside the tank. When you put the cap back on it releases the valve and the air bubble then moves from the tank into the filler neck while the fuel that was in the filler neck runs down into the tank. This leaves the filler neck empty and you can squeeze some more fuel in.
Inside the filler neck, on the left (I think) is a small black button. when you put the filler cap on, it pushes this button slightly down the neck to release the valve. You can press this when filling to activate the vent and it doesn't airlock, so you get a complete tank full of diesel without the petrol expansion air bubble.
I took the guts out of mine so I didn't have to muck about pressing daft buttons. It vented automatically.
