Or ... the BMW CM is doing an excellent job ... while MB one is actually non-existent.
Mind the SCOTT project has been active for almost ten years now.
Perhaps investment in SCOTT was much more clever move than eg. making a supercar.

Brand-image wise ...
It's not a secret BMW is very active in the internet ... and it's considering the new media very seriously. While some others are a bit more conservative ... or traditional.
Yes, eg ... MB, Porsche, Audi etc --- they all offer WEB-TVs etc ... but somehow BMW WEB-TV & it's videos are much more exposed & visible. Although BMW wasn't the first one launching such a project.
BMW use marketing (promotion, to be more clear ... especially PR & advertising) much more effectively ... using new approaches ... and beside being a design company, BMW are now transforming in a media company as well.
And, yes ... there has ever been a certain enthusiasm when comes to BMW brand, and it's fans. Especially among younger population. And still is ... not only due to the products (vehicles) but also due to communication approach which is much closer to the communication habits of today's youngsters. And being in ouch with time, BMW are able to keep BMW brand alive, exposed, and making it utterly dynamic & modern. As said many times: brand is much more than the product itself. But the product is the main foundation, of course - and the most important part of the brand promoter. Without desirable product a brand is dead.
As much BMW CM can be some times, it does a great job - for the company, for the brand, for the fans, and for the future customers.
Modern, dynamic, powerful, successful, independent, free-spirited, joy-bringing ... BMW.
Who does not want to be associated with all the above-listed characteristics?!