This may seem like a stupid bug to have figured out, but when you stall the Formula BMW, and repeatidly tap the ignition on and off, it ends up making this horrific noise like a spaceship zooming down to take you away to BMW heaven, or something.
Crap this is the wrong section. DOH
But this didn't happen in patch X10, so why now? It's not a big problem, cos you only do this when you aren't :P playing properly, but still it's not realistic...
Are you by any chance using custom sounds which clip a lot?
And the little squeaking sound sounds like the starter motor going on and off really quickly.
The FBM and MRT being powered by motorbike engines have a slightly higher pitched starter motor (which sound spot on to me).
I haven't replicated your problem yet, but if I do and get the same problem I'll post here.
Edit: Just tried it. When repeatedly tapping the ignition button in the FBM whilst in gear, the rear wheels spin ever so slightly but quick enough for it to 'skid', that's what the high pitched noise was in the FBM.
The XRR with default sounds didn't do anything like in the video posted.
Only the FBM as it wasn't the engine sounds that were going mad. Well I couldn't hear any crazy engine noises, only the tyre squeal from the starter tryin to start the car whilst in gear.
I replicated this with my twin turbo toyota supra i kept pressing the button on my g25 to start it then a uf1 came and took me away so i'm writing this message from my phone cause i'm in a ufo on lfs i got sucked into the game help
About this sound issue, its abit odd because i tryed with all the cars in LFS with default AND custom sounds yet could not re-produce what you say you are experiencing, however, when i use the FMB engine noise you posted up, i do get the noise. Maybe it is something to do with the engine files in X30? Try making a custom one in another car and see if it does the same...