I am picking this theme up from another thread, and giving it its own.

Diesel has won Le Mans 24 hrs, and it it the engine most of us use.

Using the new Gr R regs, and adding R3D for Diesel would make a sensible start.
The german HJS series uses Gr N regulations, and that is another option.
I think Diesel in rally is a good idea, if not for the top classes, then as a option for drivers to choose.

R3D is something FIA could look closer into.

What do you think ?