Just though I'd pop in this thread and see if we can have a sensible look at the Physics now some of us have been driving for 20 hours or so..
MY experiences, I'll start with my initial overall experience, as I think it sets the tone and also puts any minor observations into some perspective.
This doesn't take into account any 'possible' hidden changes to the Physics engine, all assists where 'off' and I use Arcade mode to instantly try out a range of cars, I've also raced online a bit to experience yet more cars/tyres etc.
+ Initial impression was very good indeed, taking the Cicic EK9 as a first car, the grip levels and overall demeanour of the car indicates a pretty decent handling model indeed. I would say from a user enjoyment/experience that was 9.5/10 for me..
+ Under braking you instantly notice that PD have sorted this since GT5p, tyres on the limit of locking or actually locked correctly allow little to no steering effect, much more realisitic
+ Braking also has that nice 'squirming' feel when threshold braking into a corner (ABS on '1'), it feels 'right'.
+ Weight transfer seems to readily 'felt' in a good way, Much better then GT5p
+ Overheating tyres through excessive sliding/wheelspin seems to behave correctly with the tyres quickly losing grip.
+/- The handling model is definitely forgiving (again, all assists off), I can control and largely get around 3 laps of suzuka in a high power RWD supercar with tyres that don't allow traction in the first 3 gears. I'm not saying it's easy or that it's a terrible thing, but it's not brutally unforgiving as I find some hardcore 'sims', and in a way, I don't want that, I prefer having just about most situations controllable with some very quick reactions and a bit of 'vim and verve' applied to throttle/steering.
- I'm not convinced the brakes aren't slightly wrong. The issue is, if you turn off ABS, things get quite unrealisitic for me, even half brake pressure culminates in almost locked wheels, and any slight steering input has the car going into a slide, in fact you seem to be very disadvantaged by turning ABS off, I can't stop as quickly or with a semblence of control. What really highlights something is not quite perfect is that just putting ABS to '1' has a massive effect, the car rarely slides when trail braking to an apex, and you can stamp on the pedal and you get reasonably controlled braking (still a 'nice' touch of squirming and weight transfer affecting the car's balance). The final indicator that the brakes need a little more tweaking is that it's the only assist that can't be forced off in MP. Saying all that, with ABS set to '1' I find braking quite good, so it's not like I can't get it how I want it!
- Drivetrain effects and FFB - When setting off under immense wheel spin from standing start there is zero effect on the car, and no FFB effects either. It'd be nice to have some slighty contrived tramping/torque steer and a little 'fight' in the steering, on in the case of RWD, the rear end just sliding out a little.
- Collision physics - although the cars tend to react better the GT5p, it still feels a bit numb, which on one hand shouldn't be an issue if you are a clean racer, but when PD have events where you inevitably have to get amongst other cars (TG Lotus race) it would be nice to feel (even if more contrived, I don't know) slightly better car interaction.
- Tyre grip levels - The TG lotus race, or take an McLaren MP24-12C around suzuka on the default Sports (Hard?), That's massively unrealisitically reduced grip levels, you couldn't buy tyres in the real world that behave like that.. It's entertaining on one level of course, but when 'sports' tyres on the McLaren result in almost zero grip in the first 3 gears, you realise what is going on, that to make people 'happy' with the physics, they have reduced grip levels quite far to give the impression in low performance cars of more realism, but being harsh, I'd say despite me liking it, it's not right.
Conversely, Race->Soft tyres on the McLaren resulted in not being able to break traction in any meaningful way for 3 laps of Suzuka, the grip level was insane (And again quite entertaining in a god like way tbh).
I don't know if people can discuss the physics by trying to quantify things (I've made an attempt to highlight simple conditions that show any observations that I noted). I'm not some idiot trying to discredit the game, I'm just a very keen racer who really tends to get quite into these games.
My summary would be
Intially the handling model/grip levels give the best experience I've had to date on a console, I've had a lot of fun!
I would say that my experiences so far indicate for me that it's a nice step up from GT5p, but the brakes/grip levels and some missing drive train/car interaction stuff do show where it's a little mixed up at times..
With all this talk of things improving at higher levels and no sign of tyre/fuel depletion yet in my event racing etc, I need to revisit the physics when I'm at a higher level 'if' things really do change etc.
I don't even want to mention PC sims, I'm sure with the careful choice of tyres on cars GT5 can approach the natural feel that PC sims tend to offer, but I don't actually think it's got as complex physics as the more established sims all round, maybe in a couple of areas, time may change my mind on that.