The Matmut Oreca 908 won this years LeMans championship series, even though they lost at Lemans 24h.
But a 908 could win the 24h last year.
They managed to set one fast lap after the other but at the end the slower Audi R15 Plus showed to be more reliable when driving generally slower instead of being a rocket.
The C9 is a former Lemans 24h winner and was also very successful in the group C world championship, from 1987 to 1990.
Funny is that only a Peugeot 905, the official precursor of the 908, was faster then a C9 on the Ligne Droite des Hunaudières, but during this maneuver, their engine blow because of insufficient cooling. Their max speed was 406km/h!
If you compare a LMP1 with an open wheeler, like a formula 1 car, you have to consider that a LMP1 has got a much better aerodynamics package because it's wheels and cockpit are covered. So it's plausible that a heavier but still strong on hp LMP1 can keep up.
The reason why F1 car needed so much crazy wings all other it's body some years ago, was to compensate the open wheels and the lack of a canopy.
That's also the reason why Adrian Newey has chosen to make the X1 a closed wheeler with a canopy. In other words, the X1 is a light weight LMP1, let's say a LMPX
