MP4.2+6.0

The other gain as the link mentioned is the greater rotor diameter that fits inside a given diameter wheel. That was what I remember Audi touting at the time too. But, the D3 design has done a nice job slimming down the caliper per given wheel size that also allows a bigger rotor. On mine, that factory 18's actually fit with 385mm rotors is very uncommon. Ditto on the 4.2's that can get yet smaller w/ still generous rotors.

Audi's C1 (100LS) was actually inboard rotors up front. Super 90 might have been too, but that dead ended as a model before the later Fox/first B series. NSU Ro80 also had them (the first Wankel: merged w/ Audi/VW in late 60's). As did old XJS, early Porsche's as I recall and some others. Good for unsprung weight (though all cast iron on C1), bad for heat build, road water and general big hassles. Brakes invariably ended up somewhere near an exhaust header, so were "pre-warmed" by both that and the whole drivetrain to which they were bolted. Even better on a slant I-4 w/ the dual header literally sandwiching the right side (only) brake rotor. Road spray would get under there much more than the in wheel conventional design too. Also tough on the CV joints. And, only way to service caliper hydraulics was to drop the tranny--though by today's standards it was small and pretty light. Nonetheless, I rebuilt them blind with caliper in car by unbolting and prying at (solid) rotor just so, and pulling the (very easy to remove) headpipe. Pads were do-able, though inserting spring clips into tiny drilled retainer pin holes was also blind. Put 120K miles on a 1973 C1 with them, and had a 75 C1 that moved them outboard. No difference in feel/claimed benefits, and '75 was much easier to service brakes. Still left all the other C1 reliability problems though.

Last, they were good for one other thing: brake dust! Never ever saw even a whiff of it on the 165-14's on the '73 of course with its trim rings and chrome "doggie bowl" hub caps (yeah no aspect ratio...I think that makes them something like "85 series"), despite the Metalmaster/Repco semi metallics. Definitely saw the dust on the '75, and on every Audi since.