the MFD modding competition was run a couple of times, so they are allowed (probably within reason). it depends what the challenge is as to where on the forums to put it.
Yeah they are allowed... the hard part is getting people to participate as a lot of us just don't have the time to get a mod cranked out so "on demand" like that. Get people to participate though, and it can be a lot of fun. Unless you're talking about a racing contest... which is still allowed of course.
alright, in that case: https://www.beamng.com/threads/budget-sports-car-challenge-automation-mods-only.67789/
They’re not very popular but allowed. Not many people participate in them because they require more effort than they’re willing to put into it. Your automation competition is completely fine and dandy here to the best of my knowledge.