How does PD model car behaviour so accurately?

[CustomX]

For all the flaws that people go on about, I'm constantly amazed at how well PD (seemingly) manage to model the behaviour and feel of cars. I've seen content about how they photograph the cars (for GTS that was) but I'd love some links/resources that describe more about the car behaviour and feel modeling process.

I'm also interested to hear from people who actually drive these cars in real life, whether the PD models are accurate or not. Ie. Does driving a 911 (997) in GT7 actually feel like drving that car in real life. And so on for all the cars.

 

[Hayden]

PD does a very good job on handling dynamics. Cars do behave pretty similarly to real life, and while many will be quick to point out the physics engine isn’t perfect, the vibe of each car feels accurate in my experience.

My virtual track car, 800BHP - 1800KG, Charger, behaves and reacts in a lot of similar ways to my real 300c of the same specs. (Like a bit of a pig, always on a knifes edge and with major issues with on-power oversteer if you were wondering.)


Likewise my stock 86 feels very similar in both worlds. Nimble, extremely predictable and fun.


How exactly they do it I’m not sure. I think a lot of it is figured out inside the physics engine, cross referenced with data from their tyre partner and real life data they’ve been capturing as far back as the Motec data logger system in (I think it was) GT6.

Would also be interested in learning more

 

[Chris30]

Idk how they do it, but everytime I look at them it feels like I'm actually driving a car. Makes me feel famous like i'm in the racing industry!

 

[breeminator]

The highest performance car I've ever owned is a Honda Civic Type R, and no driving game has ever felt anything like driving the real car to me. You just have so much more feel when driving a real car, from the g forces, the movement as the suspension loads up, the micro losses of grip that let you sense how much grip is available.

I have a friend who has owned several 911s, but he has only played Forza, not GT. He says the 911 in real life is easy to drive, nothing like the difficulty in Forza. I've also been in a TVR and a Ferrari owned by other people, and they didn't appear to have any difficulty at all controlling them.

Driving games have a lot of fake difficulty, IMO, to improve differentiation between different skill levels. I'm not saying that is necessarily a bad thing.

 

[G.T.Ace]

Well, FWD cars don't behave like real ones at all. GT still doesn't properly simulate lift-off oversteer for example.

 

[Nathan88]

The highest performance car I've ever owned is a Honda Civic Type R, and no driving game has ever felt anything like driving the real car to me. You just have so much more feel when driving a real car, from the g forces, the movement as the suspension loads up, the micro losses of grip that let you sense how much grip is available.

I have a friend who has owned several 911s, but he has only played Forza, not GT. He says the 911 in real life is easy to drive, nothing like the difficulty in Forza. I've also been in a TVR and a Ferrari owned by other people, and they didn't appear to have any difficulty at all controlling them.

Driving games have a lot of fake difficulty, IMO, to improve differentiation between different skill levels. I'm not saying that is necessarily a bad thing.

At legal speeds I doubt any modern performance car is difficult to control. But a quick look on YouTube shows average drivers are very much capable of putting such cars in the wall when they turn off TC. Or think they’re in Fast & Furious and attempt to drift.

 

[Lebowski]

They don't make car behaviour even remotely accurate, what on earth gives you that impression?!! I've had 5 cars in GT games and not one of them is even close, it's actually quite laughable just how wrong they get it!

 

[CustomX]

Probably a trade secret or something but I'm interested in how they actually do it. Like do they have a "car model" software engine and then adapt it for each car they add to the game. Or does each car get made from scratch?

 

[Beezer215]

I'd like to see your jaw hit the ground while trying anything on PC. I recommend never trying rF2 through a DD wheel, it will probably ruin anything Gran Turismo for you. They are making the minimalistic of physics calculations to allow 4k graphics and it still stutters on PS5's. Not to pee in the Wheaties or anything.
Edit: But to get into how they make it look real. Within the physics engine, there's a gravity coefficient. Within the cars you have different inertia calculations and that summed with a cars center of gravity, weight and suspension spring nm/dampers, the car rolls and this in turn gives it the nice matching effect to real world cars. They probably have to watch some video and get it to match by playing around with numbers but the cars look pretty good going around track. This couple with tire mechanical grip and you're off to the races. too much lateral weight transfer and around you go when the tires give from their grip to slip allowance. It's fun to fool with these values in mods for Assetto Corsa and see where the physics engine shines and where it falls short. For example, AC does NOT do karts very well.

 

[Pigems]

iRacing still has some quirks with their gravity. lol

 

[meekrab]

"Math" is the simple answer. The real world, for unknown reasons, (but very fortunately) seems to obey rules that we can write down very good approximations for as algebraic equations. From there it's just a matter of setting up the right model of the car (weight balance, suspension geometry, tire characteristics, aero) and then running the physics at a high enough resolution that "weird stuff" doesn't happen.

 

[CustomX]

sounds super simple!

 

[sodazman]

It's somewhat accurate from my experience. I have owned some of the JDM cars (S2000, Evo 6 TME, Silvia and now FK8 Civic Type R) in the game. I would say physics wise it's about 60% accurate.

 

[Meythia]

"Math" is the simple answer. The real world, for unknown reasons, (but very fortunately) seems to obey rules that we can write down very good approximations for as algebraic equations. From there it's just a matter of setting up the right model of the car (weight balance, suspension geometry, tire characteristics, aero) and then running the physics at a high enough resolution that "weird stuff" doesn't happen.

Racing is math, the only variable left is the driver.
If all drivers would be driving perfectly, it would be possible calculate which car to win on which track with pinpoint accuracy.
So if someone gets all the calculations right, it will present a game that comes close to the real thing.

 

[CustomX]

"Math" is the simple answer. The real world, for unknown reasons, (but very fortunately) seems to obey rules that we can write down very good approximations for as algebraic equations. From there it's just a matter of setting up the right model of the car (weight balance, suspension geometry, tire characteristics, aero) and then running the physics at a high enough resolution that "weird stuff" doesn't happen.

But is it really this simple? There are so many factors thrown into the mix. To name just a handful

• tyre compounds and wear
• gear shifting patterns
• slip streaming
• fuel usage

And then each of those factors has sub factors and interplay between those factors

• different tyre wear for different driving styles
• the size of the cars slipstreaming or being slip streamed
• how the fuel usage varies as the car gets lighter from more fuel being used up and different gear shifting patterns and different tyre statuses

It never ceases to amaze me how cool it is that they're able to give us such a realistic and fine tunable experience. Mind blown every time I really think about it.

 

[Hazel]

Generally, it's tyres which show the difference between game and real life.
But, run ACC on a high end pc with wheel & load cell pedals and as others have said 'you'll be blown away'...
GT7 is good for a console game but despite all the claims it is not a racing simulator rather it is a 'driving simulator' which is a whole different thing.....
Be interesting to directly compare ACC on PS5 and PC to compare the hardware capabilities.

One thing they ALL get wrong though is 4WD off-road vehicles, my Range Rover has higher acceleration and an order of magnitude more grip than the games show. (It was in a Gran Turismo game as the Range Stormer)