MB is owned by Daimler Benz actually, with Chrysler under its wings. Its the third biggest automotive group in the world, behind GM and Ford, and is the biggest in europe.
They own some pretty big names in the automotive world, with Smart, Ilmor, and McLaren to name but a few.
And its all down to Mercedes. It is because of their fantastic cars, and popularity where it counts, in sales, that the company has had enough capital to invest in such other influential businesses.