Are these mods realistic?

Hey guys long time sim racer here! I’ve been on rfactor for a very long time and have moved on to automobilista due to the tracks being utterly superior. I’m a physics enthusiast when it comes to sim racing since it makes me a much better racer in real life. The only cars I've ever used for years were only from those who made realistic physics nothing less. Notable people I can name are Niels, Renato, Jtech, Berscott, MclarenF1papa, WorkerBee, Kyuubey, etc. Some aren’t from rFactor by the way. Other than names and all their mods, there are some other realistic mods that I love for rfactor. They are CTDP 2006, CartFactor & HistorX. I’m always on the lookout for mods with realistic physics and I feel as if my game (rfactor) is almost complete in terms of that but I don't have any classic f1 mods, group c legends, or gt cars.

I know automobilista has classic f1 cars and a gt car but I like a bit more variety. I do have some questions about some mods and want to know how realistic they really are since I know there are some great physics gurus on this forum. I was hoping that one of you guys could shed some light because in my younger years, I would spend hours and hours comparing onboard videos, data and telemetry of realistic mods to confirm its realism. If I was lucky enough, I would sometimes get information on cars from several of my friends. Now that life has robbed me of time I can't do that anymore.

I wanted to know if the 1991 f1sr mod is as realistic as duke says it is because it feels slightly different than automobilista f-classic and the ffb doesn’t feel right even after calculating it on motec. The stiffness and feedback from the car to the wheel feels similar to go-karts I've felt before when turning, but the centering just feels off and forced. Now I've never driven those cars before but I had a fair share of driving both on competitive go-kart and on track. I also wanted to know if the gp79 mod is realistic. I did try several laps on it but I have never drove it in real life. Also, lurking around this forum I saw “HSO VLM GTPC” mod for ams and the 1971 F1 mod and wanted to know if they are realistic and authentic. I don’t doubt their realism but just want a confirmation and explanation if possible. They do feel great but learning from past experiences, even if the mod feels good, if it isn't based on real data then what's the point? Not pointing to the mods i’m asking about but just in general. Of course, there is also the feeling approach which I quite understand but without true documentation or values, it doesn't matter. I love those cars with a passion so knowing its authenticity would be perfect. On top of that if anyone can point me to any other realistic mods from hso or anywhere else, that would be absolutely perfect!

The reason for this passion and desire for realism is because in recent years, I was able to have the luxury of going to race tracks and driving and testing different cars which gave me a completely new experience.. This sense of similarity and proximity to the real car made me a much better racer as I've mentioned before. Now all I do is compete in go-karts, drift and track whenever I have the chance which isn’t as much as before.

That's a quite complicated question and there is no easy answer.

First of all, "realism" has two aspects, objective and subjective.

Objective means, the tire behaves as it does in real life in terms of sensitivity to load, grip, heating and cooling, directional staiblity, etc, etc. You can't replicate that properly with a commercial PC simulation, you just simplify heavily mosts aspects. That's where the code programmer's and the physics guru touch comes into play, some will try to strive for absolute correct values even if they produce a irrealistic result, some will accept irrealistic values as long as they get a realistic rersult. For example say you know that a tire has a real life lateral grip of 1.5 and you put that in your tire and get too fast laptimes. It's up to you to keep the 1.5 or go for 1.2 if that is what produces correct laptimes but in the process the car might stop behaving like the real one visibly does.

Subjective means, the tire feels to you as you would expect it, which in turns depends a lot from your own real life experience and expectations. As you say, most of us have never driven a Formula one, so it's pointless to argue about the subjetive perspective - every physics creator has its own take on it. Only the few race drivers familiar with virtual racing that have tested it can really tell if it is or not correct. 

So unless you stumble upon the usual hastened, shitty, clueless mod that was cobbled together by copy and modify vbalues of another, there is no answer to what you are asking.

Niels, Duke, Richard Wilks and people at that level just produce a well researched and delicate cocktail and compromise with what they have and to produce a result they feel is good, but I don't think you can say anything else except "I love it" or "I don't like it". Those guys are on a level way beyond "realism" and into the artist area.