Except that they aren't like that, and if someone has to regularly drive with SRF engaged in GT5, everything else is going to feel squirrelly and uncontrollable.
This topic is veering away from the original point, though, it's not entirely about the physics engine alone, it's the modification aspect of GT5 that doesn't add up in some ways. Most cars are held to some arbitrary limits of power, but more frustratingly; not everything can have a turbo or supercharger installed? Like the OP hints at, SS tires are still too grippy (though most of us have known this for a long time), but I can't entirely fault PD for that; this is still a light-sim, after all, and being on a console (and being such a large sales behemoth) needs to straddle a line between challenging and approachable. That is one area GT5 excels; sure, for people who've cut their teeth on PC sims, GT5 will always be simpler. But it is still arguably the most sim-like console driving game (FM4 being the other, but on PS3, there's no real competitor for road and race cars).
But an interesting thing happened when I went to pick up Arkham City, after forgetting about my pre-order for 3 weeks due to FM4. The guys at Game Stop, both the employees and the customers waiting behind me, were utterly confused as to how I was distracted with a game that was "too realistic". They mentioned when they buy racing games, they don't want them to be like reality, they prefer them to be easy, to jump right in and not worry about the millimetric efficiency required to master the turns of a track. And who's to tell them what they prefer is wrong? I just look at SS tires as another SRF, or TCS, or ASM; there for those that need them, for the sake of broadening GT's appeal, from the casual racer to the hardcore sim nut.
Of course, people scream for realism in most types of games, but then when cars come up, it's to hard, so then of course, "realistic racing sucks" in their mind, because they're no good at it, and can't be bothered to learn.
Rant over.
I don't think either T10 or PD should be bothered with what the general "gaming store community" has to say, tbh. At least unless/until there's some form of substantial evidence that arcade sells better for racing, a point that GT has been destroying for the past 1.5 decades.
Quick OT here, if you'll pardon.
I have a feeling you'll love it. It's different in ways that are sublime, but in others hard to describe. The cars are livelier on their suspensions. When the tires roar, it sounds like you're abusing a set of four tires. Like I said, it caused me to smell burned rubber! The graphics are terrific, if a bit CG in different ways from GT5, so Photo Mode should be a hoot. And that modification system and Livery Editor are just too hip for words. But the feel is different, T10 is doing something unorthodox. Some can connect with it well, some like me struggle, and some hate the physics completely. You really have to try it.
I definitely intend to.
As for GT5's mods, yeah, they're a mixed bag, kind of arbitrary. A few cars which should accept a turbo or supercharger can't. Some which shouldn't without modifying, can. And Kaz decides how far up the performance ladder every car can go, which is a source of irritation for some people. I don't mind because my "sweet band" is in the range of 300-400hp for the most part. You have grunt but aren't flying around the track at crazy speeds. Less power means closer, more competitive races, and a less spread out field, great for Photo Mode, which I may finally get to play with! I still have my monsters, like a Ford GT at 700 plus, but I really prefer less power. One of my faves is the CR-Z TC in the new DLC - lot of rhyming initials there

- which only has 200 hp. I know a lot of people loves their supercars, but some of us love cars that are super in their own way.
As for turning off ABS, it's because even at 1, all the other aids seem to be turned on one to three clicks, and you can't disable them. It gives you a car that you still have to drive properly, it's not arcade or anything, but the cars are still too poised, polite and safe to me. After turning off ABS and giving the cars a go, they feel much more alive. Not quite as vivid as the cars in Forza 4, but close enough, and I can still drive aggressively. And in racing, you can tune a car however you want, within regs. And in GT5, there aren't any that I don't make up.
The problems with GT5's tuning/upgrading don't just come in the form of turbo/superchargers though.
First off,
any car with enough room under the hood, or under the car can be turbo or supercharged.
Any car. There's even rear-mounted "secret" turbo kits out there so nobody can tell you have one.
But more then that, the prices are absolutely ridiculous, on EVERYTHING. $500 for a freaking air filter? $20,000 for a turbo that only gains 40HP?
And then there's engine mods, 1K RPM gain from each stage? Where'd that come from? 1-3K for an ECU? Why can't I choose where to put the rev-limiter? On cars like the Subaru's, which PD has intentionally raised the limiter in ridiculous amounts, it'd be nice fot AT users to be allowed to race in the powerband, I would think, rather then over-rev up to 8K+ RPM on a car that loses power starting before 7K RPM.
Furthermore, drivetrain mods, more specifically, not being able to simply swap a rear, which is the most common real-world drivetrain modification people make, at least in the States, and we might just have enough with it here to make that worldwide. That's a staple upgrade for many people, and not just drag racers, and it's not even in GT1,2,3,4, or 5
at all.
Suspension, pretty limited, always bought in incredibly expensive kits, with undetermined settings.
Weight reductions, no idea what they are, specifically, limit weight reductions on cars much like the "max HP" most cars get limited to. Problem with weight reduction though, is weight is the PP's favorite buddy, so typically, heavy cars just can't fit into any PP category well at all. IIRC, a Lamborghini GT car was made IRL and weighed in around 2400LBS. In GT5 the best you can do is around 27-2800LBS. 👎
Aerodynamics, well, you can't really even buy them. This is what you need to make any "stock" car, run with racing cars, but PD won't let you. In fact, you still can't add front aero to any car you can't RM.

For cars like the ACR, with this feature on the car off showroom floor, this is a major slap in the face, but in any case, should be achievable on all cars, to what degree is the only question.
RM's, some are good, some are terrible, some "okay". Basically all depend on whether PD gave them downforce or not, and for many of them, it's 15-20 front downforce. While that would work if we had fields of cars limited to 15-20 front downforce, we don't. This renders most RM cars useless, yet again. RM's were one of the coolest things in GT1 and GT2, and have since been dropped by the wayside for unspecified reasons. Now we get some back, and the uses are all limited pretty heavily, the Vettes are just race cars as they should be, but still lack enough downforce to truly rival the other GT cars in it's class, which typically have 50/70 downforce over the RM's max 35/60 downforce. I don't think there's a single RM in the game that can keep up fairly with any of it's "rival racing class" cars. Even the EVO and STI are to light to be equal to rally cars, not enough downforce to be racing cars.
So there's a huge chunk of modification failure on PD's part. And I haven't even touched the "tuning" bits of it.
And to me, 90+% of it is simple, "what the hell, PD?", type of stuff.
I was more referring to this general attitude that somehow less grip = more realistic. If that were true, we'd all be pirouetting across intersections and in front of buses on our way to work.
On the SRF issue - I had to drive with that on in the GTR time trial yesterday, man it felt downright strange. I'm sure I could've gone faster without it too.
Highly unlikely, if you know
anything about SRF and how it works.
I don't know how Kaz worked out the modification "rules", they are a bit strange. I daresay some cars which can't have a supercharger, for example, simply wouldn't have the underbonnet space for one. Regarding tyres, they are just placeholders for classes of tyre (touring, sports tyres, semis, r-comps etc).
Name the car without space for a turbo or supercharger added, please. I'm sure there's at least one or two in GT5.- But even if there's 10, surely we won't let that detract from the fact that most every car can have one added, right?