Don't forget that VW/Audi is also working on the Diesotto; they are not as advanced as MB though, and their motor need special synthetic petrol to work. The Diesotto of MB uses conventionnal petrol.

As Artist said, you can't compare Mercedes-Benz with Saab.

1) MB invented the car
2) MB made the first Diesel on a production car
3) MB creates the DiesOtto

Seems logical, eh!