Harman Kardon is part of Harman International and they provide an OEM for a bunch of different automakers. The new Harley Touring bikes have HK sound systems. Nothing wrong with them. Altec Lansing is part of the same group and they do most of the rest of the luxury brands. jBL is also part and does a lot of the Ford systems. Infinity is in there too. About the only companies that do OEM work that are not part of the conglomerate are Bose (GM and Nissan/Infiniti), Rockford (Nissan trucks) and Kicker (Chrysler SRT vehicles).
for real though, i heard a bentley stereo once, it was absolutley amazing, same thing with range rovers.... my uncle had an S500 and i didnt really think that the stereo sounded that good, but my dad used to have a 2000 lexus, and ****, that thing had a system in it for OEM