The rational thing to do here, of course, is to say “**** that, we’re driving and saving ourselves money.” and I would understand if you did.
However, the fact that it’s a stag-do means that all rational behaviour is thrown out of the window in favour of the group dynamic.
A few years ago, I went to a stag do in Brighton with a bunch of lads, all of who were coming from North Wales/Chester area. Naturally, coming from Bristol, I got the train down and waited there for them. They all got a coach. I was already a bit of an outsider in the group as it was, but I regretted not just driving up there and getting the coach down with them as it would have inveigled me into the group a lot more quickly.
Much as it’ll piss you off, get the train matey. At least you won’t be worried about driving, parking etc and you won’t be the arseholes who insisted on doing things their own way at the stag-do.