i use a mondeo (mk2) for bike/surf/camping. Its a bit long in the tooth, however
biking : can (just) get 5 big bikes in the back with all seats up, with wheels/pedals off. 4 is easy, the mk3 mondeo (2000-2007ish) is a bit bigger/easier
surfing : a 6’6 goes in the back easily. 7’3 can go in just intruding into the passenger armspace a little, a 10′ board will fit, but touch the windscreen so a bit antisocial/difficult. that’s with the wider of the rear seats folded
camping : rear seats fold to form a completely flat load bed. you can camp with a bike and 2 boards, all in the car. the load space is about 6’6 long, could be longer if you slid the front seats forwards.
I’d imagine a passat is similar, but I don’t know them very well.
how about an MPV? the extra height would be very welcome when it comes to loading bikes/camping in it?