Driving from Croatia to the UK, what are the must sees?

[petrolveins]

As per the title, I'm driving to Croatia in the summer, Dubrovnik specifically, time is tight on the way so no time for sightseeing, but on the return I'm hoping to take about a week. The rough route plan takes me through Croatia, Slovenia, Austria, Germany, Luxembourg, Belgium, France and home. The only plans I have so far are the BMW, Mercedes-Benz and Porsche museums in Munich and Stuttgart. I'm not doing the ring this trip, I'm more keen to find some stunning scenery and good roads, and anything of automotive interest along the way. Would love to find a very tall mountain and drive to the top if possible too. I very much want to stay away from the tourist hotspots, aside from a few cities, I just want to find stunning views and roads, but I have got fuel to think about so don't want to detour too far off.

What things would people recommend along the way? Google map links would be greatly appreciated. Any general tips or advice to a 19yo taking his 330i to mainland Europe for the first time would be helpful too.

Also not sure where was best to put the thread, so I popped it here, Mods feel free to move.