The Germans did a few good things in the 90s. AMG merged with Mercedes and the AMG models became more "affordable" and better in many ways. The C36 was the first car made that way, and they were great cars. Okay, the C36 was still expensive, but not exotic car bucks like the AMG unique models produced previously.
Porsche was financially a disaster at the beginning of the 90s. The US market fell apart for them, and sales of the 911 were dismal. They'd raised prices dramatically in the 80s to capture windfall yuppie profits, but it came crashing down with the early 90s recession. Luckily, they bounced back thanks mostly to the Boxster, giving them a much lower priced car to get some volumes going. If the Boxster had been another 924 they probably would be hanging out with Saab somewhere right now.
Audi found success with the A4 in the late 90s. The car had marginal build quality, but looked good and sold well.
The E36 BMW was a strong product. It sold well enough thanks to aggressive pricing (you could buy an entry level 3-series for not much more than an Accord) and helped BMW weather the 90s recession. Build quality wasn't Toyota-like but the cars were simple enough that people didn't drive them off cliffs to get away from them.
Overall the 90s wasn't the strong decade for the Germans that it was for the Japanese. The German makes were suddenly staring at competition that was far more reliable at 75% of the price. In the 80s the only competition the Germans faced was from England and Italy. Mercedes, Audi and BMW needed to be in full panic mode the instant the LS400 hit the market. Whoops.