Yep, they are possibly the most evenly matched Le Mans cars in the game, was doing my 24 hour Le Mans II and they were pretty close even at the end of the race, they are the only cars that don't lap each other in this race:
http://i.imgur.com/z7pMqVB.png
Well, they are not only the most evenly matched but they are the best cars in the game after the FGT. I am saying this based on how the AI and my B-Spec driver handles them because if I am to talk about personal experience then every Le Mans Group C car is pretty much evenly matched with only tenths of a second difference.
Based on how the AI/B-Spec handles the cars it's like this:
0.
Formula Gran Turismo
1.
Minolta Toyota/Sauber C9
2.
Nissan R92 CP
3.
Mazda 787B
4.
Nissan R89 C
5.
Jaguar XJR-9
6.
Audi R8
7.
Toyota GT-One/BMW V12 LMR/Bentley Speed 8/Peugeot 905 (These 4 all of them are as evenly matched as the Minolta and the Sauber are to each other, whenever they race with the AI, they usually stick to the same distance/time they started the race separated from each other, the 905 takes a bit of time to shift but for some reason, likely better acceleration, it can keep up with the other 3, well, it's also worth noting that the 905 is likely the worst Group C car in the game).
9.
Pescarolo GV5
10.
Pescarolo C60
11.
Mercedes CLK-GTR
12.
Nissan R390 GT1
13.
Chaparral 2J (should note here that in some tracks I've seen this 2J actually gaining in time against either the Nissan R390 but in most of them it falls behind)
14.
Esperante GTR1
15.
McLaren F1 GTR
16.
Gillet Vertigo
17.
Pagani Zonda LM
18.
Ford GT LM
19.
Nissan GTR LM
20.
Dodge Viper Team Oreca