You are always welcomed in the BMW's headquarter in Munich even if you don't have your own BMW and not going to buy it (but I think that after visiting this place you will).
The BMW's headquarters are called BMW Welt (from the German for "world"). It is the largest BMW center - about 100 customers but their cars from it everyday! But this is not the only feature of this center - interactive exhibits showcasing the company's operations in R&D, design and production, as well as concert venues and conference rooms and even a Junior Campus for younger guests.
Visitors to BMW Welt can also visit the local BMW Museum where they can see about 120 original exemplars covering 90 years of BMW history. 25 exhibition areas meet about 400,000 visitors each year. Hope this museum will be added soon to Carakoom list of tours so you can see it here.