The DTM organisation has for the first time in 30 years decided to change the regulations mid-season, in order to allow Mercedes to further develop their struggling C-Coupé model, according to Auto Motor & Sport.

The decision was jointly taken yesterday in a meeting between the DTM organisation, Audi, BMW and Mercedes.

This means that Mercedes are allowed to break the homologation deadline to develop new parts until September 28th, as well as completing an exclusive test day. Audi and BMW will not be granted the same exceptions and have their chassis and aerodynamic features of the RS 5 and M4 models frozen until the end of 2015.

The Mercedes drivers have struggled severely in the first three races of the year, although Christian Vietoris’ was able to take a surprise victory in the rain chaos at Oschersleben. The C-Coupé has been reported to be four tenths of a second slower per kilometer compared to the Audi and BMW.