No, it's not bad at all for a day trip! It's a lot of fun, especially being in the convoy of ///M's... Last year when we visited Hamann and Hartge, they were day trips. We even included Hooters in Neunkirchen on the way back from Hartge. Time goes by pretty fast in the M Flight convoy due to it being entertaining. 3 hour one way drives feel only like about half the time as opposed to driving alone on the Autobahn. We will also visit Lumma Tuning
http://www.lumma-tuning.de/ in Winterlingen and Alpina
http://www.alpina-automobiles.com/en/home.html in Buchloe. Those will be about 3 hour drives one way from K-Town too...