The Porsche Cup car was supposed to be quite realistic in RaceRoom and especially in iRacing.
Alex Hodgkison: "It was the very first car I eased myself into Sector 3 with and it's easily the car I've spent the most time on".
iRacing also put a lot of effort to get physics right:
Lastly, does this feel realistic?
Elliott Skeer: "I’ve done a couple laps at each track I’ve raced them at, with the setup directly off the real racecar. And my answer to that is…. Holy Fuching Sh!t Oh My God YES! Every tendency that I’ve picked up to drive this car properly works exactly as is on here. Little quirks that happen at Watkins or Sebring happen the exact same way. I’m in absolute love with this car.
Top job iRacing, this is next level!"
https://www.reddit.com/r/iRacing/comments/5qdnbb/porsche_cup_driver_elliott_skeer_faq_and_review/
on a question regarding grip he answered:
"On the limit? This car is pretty good on the limit as is. I'd say a more aggressive release point though. There's a 5* yaw window here that really lets you save a slide, and that's non existent in the real car. Needs a point of no return (sorry iRacers who think it's too snappy )"
I didn't know about him, so checked his bio:
"He also continued to coach professionally and
started to work with iRacing as a car dynamics developer."
I dug a little more and saw this:
"... if you knew how much work went into getting the numbers on the car damn accurate, down to specs that you wouldn't even think about. I've driven it with the numbers bang on exact compared to the real car in every way, trust me it's not what you would want released. Some small compromises were made in places, less than you would actually think too."
He also said it's probably the most realistic car in a sim. Problem is I saw similar claims few times
But I think it's because iRacing version matches his personal perception of driving it.
But other drivers who raced it in reality didn't gave it such good review/opinions.
Here's one at 11:40:
and he said GT cars in iRacing are more realistic.
There were much more critical opinions. Still, Nicki Thiim tentatively ranked iRacing's version better than in AC(2nd) or RaceRoom(3rd) in his (in)famous comparison:
But I'm not sure if he raced this car IRL.
There's also AMS "Boxer Cup". Unbranded 2015
Porsche 911 GT3 Cup.
It seems ok, except perhaps has too little grip (I know it's not GT3 class car).
I wonder how realistic the upcoming version in rFactor 2 will be. I guess not as realistic as Porsche's private mod, that's used for training.
It would be interesting to get real Cup drivers feedback on upcoming rF2's version. AFAIK Nicki Thiim doesn't use rF2. I've read he didn't wan't to try Aston Martin because dashboard was way off in rF2
It's fascinating to me - a comparison how close to reality(in therms of handling) can top sims make a car. For me there are still substantial differences in handling (and especially FFB) with the same car. Probably partially because, I don't try to exactly match setup - only change few most important things from defaults in a sim.
rF2's physics engine is quite capable(especially tire model) and recently S397 proved they can make it very very realistic, with Tatuus cars. But my guess is that they didn't get so much data and feedback from Porsche and didn't put so much effort to make this one.
Anyway 99,9% users will never race the real car, but it's good to know a mod doesn't have fantasy physics.