Glad you enjoyed your trip as I, too, love travelling in Germany -- esp. by car with the autobahns!

Glad the hotels also treated you well, next time you should try the Marriott Berlin which has a superlative lounge, is very well located and has recently undergone a renovation of its guest rooms.

By the way, I prefer Dusseldorf's Alt beer to Cologne's Kolsch, but that is just my opinion.