Was lucky enough to see Grp B's in action several times.   I have watched F1, Le Mans 24hrs (Bikes and cars) World SuperBikes, IOM TT, BTCC, German Touring cars, Irish Road races (NW 200, Tandragee 100) and the GRP B was the best. 
It had action, danger, suspense...........High Octane thrills a plenty, often just a few feet away.  Something about a Welsh Forest at 2am, waiting for Vartenan, Rorhl, Mouton  

 etc.  Pity it didn't last.
I remember the Henri Toivonen accident, I also remember Tony Pond Crashing his Rover Vistesse in Knowsley Safari Park (on the 1st Stage of the RAC 1984.  Perks of living near Chester.  Also met Murray Walker driving a new Rover 216..........