Really? Do you have any evidence to suggest this? Do most mountain bikers already mainly drive to get to their trails?
No peer reviewed PhD theses I'm afraid. There's plenty of anecdotal evidence. Look at Strava - how many MTB rides start from anywhere other than the main car parks at a location - very few.
So, it's ok that you do it, but not for newcomers? Would you be willing to stop riding those trails in order to allow others to do so?
You love misquoting me to suit your point don't you? I said it wouldn't improve it, not that I don't welcome it. I don't really drive to the trails anyway. I sometimes drive a bit closer, but not to the trails themselves - I get a better ride, and avoid getting caught up with everyone else who does drive to the trails.
No I wouldn't be prepared to stop riding local trails solely so other people can, well done for your philanthropy. No problem with you calling me selfish, probably am. I will nurture new riders - two friends have got into riding in the last year and I've offered both advice, been riding with them etc, but I really struggle with seeing any environmental benefit to folk taking up mountain biking, and you've yet to offer anything whatsoever.