Old B group cars are slower not in straight line but in overall they have been slower since 2010 or so. mainly because of chassis and suspension. Old cars dont have that much grip that modern cars have even tho they might have been faster on straight line because of that insane power but its been over 10 years since B group cars can be even thought to be in same times as WRC:s
And today wrc cars have much more downforce. They are like F1 on gravel. Can see on curves on tarmac roads how fast the take the corners. When group B took the corners sideways instead
I think it is impossible to actually measure this, but Group A which replaced the Group B became faster just after a few seasons. If you look for the classic Mcrae moments in his white Subaru (yes, white back then) Legacy or the Lancia Deltas with the Martini livery - those cars were faster, and we are talking about 1991/2/3 here. Advancements in the tires, suspension and brakes made that happen. Juha Kankkunen actively raced in Group B, Group A and 2 litre WRC cars. He (I think it was him) said back in the 1987, when he moved to the Lancia after Gr. B was banned in 1986, that he could drove with just one hand after driving the insane 205 T16 just a few weeks maybe months earlier. And just 3 or 4 seasons later those cars became faster with half the power of the Gr B. In 2010, he drove Rally Finland with the Focus WRC and said that the engine is kinda not much to write home about, but stated the suspension and brakes are amazing. Group B was the greatest, but it is good they banned it. Those cars were dangerous AF and had almost nothing in common with the regular, production cars. The roll cages for example were a joke. The ban gave us amazing second evolution Group A cars like Lancia Delta HF Integrale, Toyota Celica ST205 and paved the way for the first 2 litre WRC cars in 1998 (Peugeot 206, iconic Subaru Impreza 22B) and made space for the rear wheel drive BMW M3s and Ford Sierras. Watch Patrick Snijers- BMW M3 E30- Rally Manx 88 Some videos to check: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BNDqJMTpnjk.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vH4z5OI5aNY.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nWRdqabMIEM.html
