Oh no dude no breaking. To the contrary, it will make you guys very happy. I don't know the details but 1.15 is supposed to add a lot of extra options for physics modding. Afaik, no radical fmod updates are planned for 1.15.Where is this information coming from @SunBro ?
Edit: Oh you are guessing... well I hope it is not going to break things up, basically only sound has been breaking car mods in the past.
Edit: I was guessing the details of changes. It's a fact that @kunos made some updates for modders in 1.15
Edit 2: He even added some other universal optional features like "abs effect"(don't remember the exact name) which will make the wheel rattle when abs comes into effect.