Originally Posted by MP4.2+6.0

The answer to your question is typically ease of manufacturing. With each generation of Audi I have owned, I have seen more parts rolled up into subassemblies and more fasteners that are quick to attach. Maintenance is usually secondary. If you see Audi's built on the line today, it is highly automated and indeed subassemblies are loaded toward the lines from all of below, the sides and above depending on what it is. They really seem to avoid trying to have much of anything that takes judgment, fitting or special hand holding at the point it bolts, scorers or clips to the body as it heads down the main line. These would be an the drivetrain part of the subassembly, which happens on another line and then meets w/ the body line (at least on their newest A3 line I saw last year). I expect the same principles apply there too.

And yes, of course someone could make these aftermarket. And being a D body, they probably never will. Pretty much like the C's for that matter--having owned four generations of those--even with a fair amount more volume there. Only the B's get much aftermarket stuff (even more so now w/ the A4 and A5 sisters and Q5 cousin), plus VW type stuff that crosses over to the A3, TT, etc. It could be an aftermarket bushing off of something like an S4 might work, but it is both bar diameter and clamping cup size dependent. You would almost need to work at a parts counter or own both to ever be able to compare.