Well if you're looking for an uber-hardcore sim this is probably not it. In an attempt to break the harder=more realistic mentality, most of the cars have a little more grip than you might be used to from iRacing or other sims. Partly based on feedback of many real racers who often comment that sim cars have too little grip compared to real life counterparts and partly down to the conservative default setups - if you start tweaking things you can make it as undriveable as you like
This doesn't mean it's easy though, once you start pushing the limits you can feel the tyres letting go and you really have to wrestle hard to hang on. I really like how this works because you can get used to the car quickly, but becoming fast takes real skill and effort. For all it's other pre-production flaws i actually think the tyre and suspension model is extremely good. I know something is right when i load it up for a quick couple of laps and i'm still there 2hrs later trying to find that extra tenth.
There's more cars than i list here but the noteworthy ones are as follows:
The best by far (for me anyway) is the Areal Atom. This thing just begs to be thrashed and loves going sideways. Very controllable. Reminds me of some of the cars in GTL
The Audi LeMans Prototype has the most 'mature' physics as this is the first one that Ben Collins has contributed to. (he'll be looking at the others in time). He's said that this car is now the closest he's felt to a proper LM simulator.
The Caterham is the latest addition and has a lot of character. Quite a handful but oddly addictive - currently needs a perfect controller setup to avoid massive tank slap.
The DTM is pretty nice. Bags of grip up to a point and then it just lets go. Can feel a bit disconnected sometimes. It's OK but doesn't quite give me the buzz of the atom or caterham.
The 68,77 and 86 F1's are all well done. The 68 slides nicely and really makes you smile when you get it right. This feels the most natural of the 3. The 77 scares me silly, good for a couple of laps just to be grateful you weren't a 70's racing driver. The 86 feels OK but for some reason i just didn't connect with it. Needs a bit more work i think.
The kart is borked.
Generally each class has at least one car that handles well so there will be something to your liking. The controller/ff is also working a lot better for me in the latest build (111). Bear in mind that as it isn't destined for release for another 12 months, it pushes current gen hardware to the limit. It looks awesome but you'll need a decent rig.
Also rF2 is very close on the horizon, if you are looking for something less life consuming than IR we'll be having a ton of races here at SimHQ - or you can pick up rF1 and join us in the meantime