[Graham]

Is this 1994 Merc permitted in Event 3 Procars?

Yes it is a Mercedes Class C and is in the Event 3 car list.

There is a note at the top of the regs to "pre-1994 DTM cars", that's why I asked.

(oops, just read it again on a full sized screen and it says pre-2014!. As you were!)

Yes the DTM championship stopped being a “saloon” based competition after that, and effectively became a GT3 race