Strange. Most likely a bug, although probably nobody will have an issue with this.

The new series in MOTORSPORT - Endurance Prototypes announces two cars to be part of it: Mercedes Benz C11 and Mazda 787B.

I was wondering about 2 tiers:

Tiers 2 + 12: None of the above cars are here. It's the Porsche 962C and the Jaguar XJR9 only.

BTW: You don't need the Mercedes to complete this series 100%. The Mazda alone can do it (plus the other 2 ones, obviously). PR 88 needed. Mazda full-up is 89.