Relax, people. It's a one-off vehicle. The article states BMW has no plans to put this vehicle into production. http://autos.yahoo.com/articles/autos_content_landing_pages/1786/caught-testing-bmw-m3-pickup/
I think it was a styling exercise, perhaps inspired by Volkwagen's Microbus showcar. BMW had no equivalent product to that, nor did they have an equivalent product for another Volkswagen product, which was a Volkswagen Rabbit based pickup.