I just realized that a lot of the race cars that were last seen in GT6 were overall winners of the LM24, namely the following:
Audi R8 (The 2001 and 2005 winners were both last seen in GT6.)
Audi R10 TDI (2006 winner)
Bentley Speed 8 (2003 winner - the first overall win for Bentley in over 70 years!)
BMW V12 LMR (1999 winner)
Peugeot 905 (1992 winner)
And this trend seems to extend to the inclusion of other prototypes, like the Jaguar XJR-9 and Mercedes-Benz Sauber C9, which respectively won in 1988 and 1989. It even seems to extend to non-prototypes, like the McLaren F1 GTR that won in 1995, so I think that the Porsche 911 GT1 that won in 1998 could be added - likely as a Gr.2 machine.
I'd love for these prototypes to return as part of Gr.1, especially the Bentley. However, for Audi, we already have two versions of the R18, one of which being the car that won the 2011 LM24. Still, if I had to pick between the two iterations of the R8 and the R10, I'd likely pick the 2001 R8, as it's the car that seemed to be near the start of Audi's streak of overall wins at Le Mans, not to mention being the namesake of the R8 road car. And I know that Peugeot and BMW both have more contemporary prototypes, with the 9X8 and the M Hybrid V8 respectively, but whether those cars will be Le Mans winners is yet to be seen.
But on the other hand, you can see that the Gr.1 cars that won the LM24 are also much more expensive, and we do have prototypes that didn't necessarily win at Le Mans, like the 2010 version of the Peugeot 908. The prior year's version of the 908 did win overall, but in 2010, the win went to an Audi R15. Then there's also the 1992 Nissan R92CP, which as I may've implied earlier, didn't win that year, as the Peugeot 905 won instead. Finally, there's the, uh, notable GT-R LM Nismo, which very much did not win in 2015.
I'd also like to see the Mazda RT24-P, for what I'd call a notable reason: unlike the VGT, the RT24-P isn't powered by a rotary, but rather a turbocharged I4. I think this would very much set it apart from the Gr.1-spec VGT, aside from the RT24-P also being a non-VGT car. The Nissan Onroak DPi could similarly be a nice addition, if only to show what happened to Nissan's prototype program after the, uh, shortcomings of the GT-R LM Nismo.
Of course, this is without mentioning the real neat LMH/GTP cars I'd like to see, and the ones that are upcoming, too. I just hope some of the automakers not in the prototype business end up making a VGT that can enter Gr.1, like we'll see with Genesis. Here's hoping GM Design makes a prototype racer modeled on the C8 Corvette, haha!