First of all, it's really cool to see my car in LFS!
Everything looks really good and you integrated the interior nicely. I like the backfire sound aswell, not too loud, not too muffeled.
There are a few technical thing I noticed, however:
-The gearing is slightly too long. I don't know the exact ratios, but my car tops out way earlier in each gear.
-The xDrive should be more rear biased, since it only "activates" the front axle if the rear slips (it's like a reverse Haldex gen 5). Also it has open diffs at both axles (they are "locked" by braking wheels individually). Good way to simulate this would be adding around 40% lock on both axles and very low preload. Honestly, I can only speak for the rear axle, since i've never driven an AWD Beamer.
-Caster should be close to 0.000mm for a road car.
Looking forward to the next update