Perhaps "production" is the key here..... could it be that the engine shown was a DTM specific race only engine? Just speculating here as I really don't know much about MB engine history. Hmmm... maybe it was built by Ilmor Engineering for the MB DTM effort back then? They do build the MB F1 engines for McLaren and as far as I know MB doesn't make a V10 used in any "production" applications like the ones used up until recently in F1, nor do they make a "production" V8 as small as the 3 liter units currently used in F1. Both were/are badged as MB but are designed and built by Ilmor. Ilmor being primarily owned by MB nowadays.

Heh, maybe I know more than I realized!