The new 606-style fan clutch with plastic blades triggers at a higher temp than the old 603 clutch with metal blades - I think. Mercedes printed specs for the old but not for the new. This is just a theory, but it would improve MPG due to less drag and higher engine temps (95C is more efficient than 80C). Mine runs at 90-95C almost all the time but very rarely touches 100C.
If yours is getting to 100C+ with a new clutch, the radiator is #1 prime suspect...
