I want more racing cars from other classes, i know Endurance is the hottest thing in racing right now, but there has some fun cars that i wanted be in the game
Some Exemples
-Any Modern Non-F1 Formula Car
-Ford Mustang Black Horse R Challenge
-Toyota 86 Cup North America
-Toyota Corolla TCR
-Supercars New Gen
-NASCAR Trucks
-Stock Car Brazil New Gen
-Some oddball racing cars like The Tubarão MC40 based of Ford GT or any pickup truck racer
You can build a Dark Horse R Challenge car out of the Dark Horse road car. The Challenge cars aren't really that heavily modified, and with how T10 likes to make race cars fully adjustable out of the box even when real life cars have spec parts that can't be adjusted, you would probably end up with a more accurate one... The only thing is the interior wouldn't look right since we can't properly strip them.
While I don't want them to start adding back SUVs and Ford Raptors and stuff, I'd love to see them to add vintage 2WD minitrucks to make the SCCA RaceTruck Challenge series. They should be light, draft well, and with no weight over the rear ends, should be pretty playful. Some interesting names went through the series, like the Archer brothers, Steve Saleen, Pete Halsmer, Petey Cunningham, Tommy Kendall, and even Jeremy Shaw, the RLM commentator for lots of ALMS and other series endurance races.

As far as other racing trucks go, the ACTC truck class is kinda cool, with pretty stock-car looking trucks:
And, while it would never happen because they aren't real, but the DMR VTS65 mod for NR2003 with hypothetical '60s NASCAR trucks is super cool and I would race the hell out of these things:


Tis a good point. If they kept the DBR9 then it might be worth adding another GT1. But given the Aston is gone it would just be on its own.
Speaking of the GT500 Nissan- it belies all logic that they add that and not the NSX and Supra of the same era. Or even tell us when the Nissan dropped that its two nemesis from the era were a future addition. The BMW M4 DTM of FM5 was the same. The 360 era games had all three of the GT500 cars from launch. Plus both the DTM makes. There's two popular championships both in single player and multiplayer for fans to enjoy.
This is something T10 has always been kinda bad at. Even in past games where we had more options from different classes, they often get the specs for them from different series/eras/trims so cars that should be competitive aren't really that close.
I think it contributes a lot to the feeling of a lack of progression on the content side of things, even though they have been adding cars every month. The only time it really feels like we got something "new" was the NASCAR update, and it was one of the best received and best utilized updates so far. While NASCAR ticked a slightly different/"new" box in that it's a little bit different discipline than Forza's normal road racing, I don't see why a GT4 update, or classic GT1 update, or SuperTouring or DTM or JGTC or any of dozens of other series/regulation sets wouldn't also be a popular update.
While it still wasn't utilized as well as it could have been, the NASCAR update definitely energized the community with what felt like a somewhat cohesive new series to try. It had multiple manufacturer choices to represent, new canvases for painters, a new type of car for tuners to tackle, a handful of relevant tracks were already in the game, and it justified its own hopper being set up that, to this day, is (relatively speaking) still fairly popular.
Compare that to something like the introduction of the GT500 Skyline. It was a new race car based on a super iconic model, from a previously unrepresented class that is highly regarded by racing fans and underrepresented in modern racing games... but it was basically an afterthought that many people have never even driven and many almost forget was added to the game. There was nothing to do with it as it had no rivals in the game, there's one relevant feeling track for it, and it just got dumped in a class where it doesn't feel like it belongs really. Since you had to jump through a bunch of stupid hoops to get it, the majority of the community doesn't even have it which means there isn't much of a "market" for liveries or tunes. Had they paired it with the NSX and Supra and maybe a few GT300 cars to go with them, along with SUGO or Fuji, and a JGTC hopper, it could have been a big deal.