Tyres and weight of course. Just watched incar of R18 and F1 Alonso - same speed on fast corners, little less speed in LMP1 on slow and midspeed ones, little bit longer acceleration, top speed the same.

So, yep - weight and tyres.

Very interesting to compare group C and F1. Group C was a monster on straights. But slower on lap times due to weight.


--

sportcars-history.com