I'm just saying if I have a vehicle made out of good parts, it better not just randomly break. That's just frustrating gameplay. There is no fun to be had with that. I mentioned the amount of time a BM is. If it lasts 6 in-game hours, then in order for randomness of break downs to be effective, it would have to weighted so that the chance of randomly breaking down within a 6 in-game hours span is almost guaranteed. This means even on non-BM days, your vehicle is going to randomly break down 4 or more times a day. No way. Random is good for a lot of things, but it just wouldn't work here.
Look at Days Gone. Vehicle maintenance is top priority. You are pretty safe on the vehicle but if you drive poorly or if things hit your bike, it will break. It doesn't just happen randomly and it doesn't need to because their system works. Leaving the randomness out of it, and making vehicles more vulnerable to being damaged is something that fits in a survival game. The zombies need to actively attempt to disable your vehicle on horde night such that a few good hits makes it break down. In Days Gone, it's not just the terrain and zombies, it's also other NPCs shooting. There may even be other ways for it to break down... just not randomly.
You would then have to further justify these random breakings. Your axe, your pistol, your club, your bow, your shoes, your nerdy glasses, your forge would also be subject to randomly breaking.