BeamNG actually ticks all these boxes, as much as it’s known as the crashy smashy game. Every component of the car can be swapped out, including everything from body panels to engine components, to suspension and tires.

The tuning is also incredibly in-depth and even more so once you start getting into the modding scene, which is huge.

If this isn’t already a staple of your library, I can’t recommend it enough.

I mean there is Forza Motorsport (2023). Personally i'm not a big fan of this particular iteration but its pretty much the only game which checks all your boxes on Steam.

Or you could check out PS2 Emulation with PCSX2 and the Spec II Mod for GT4. PS3 Emulation for GT5 and 6 still isnt perfect and pretty demanding for the hardware but also worth a look. I think there is the "master mod" to spice things up? Like why search for an imitation if you can have the original?

Motor Town isn't exactly what you want, it is more like GTA but just the car jobs.

The physics feel good though, like reallly good.

https://store.steampowered.com/app/1369670/Motor_Town_Behind_The_Wheel/

RetroArch... Relive those good old days!

Most or all the franchises with a bunch of good legacy entries have turned into money grubbing grinds, including Gran Turismo, or instant gratification titles like Forza Horizon.

So I have nothing to recommend :(

Maybe Project Motor Racing? It's out November and has a Career mode, but idk if that's what you're looking for. I don't think it has any slow street cars.

the best racing/driving game I know is Motor Town: Behind the Wheel.

Don't let the graphics fool you. Check out nexusmods, get the most popular ones and hoon to your hearts content -- it's not quite as deep as BeamNG or My Summer Car (which I also recommend, but they are not my favorites), but you can do some very goofy shit (1000HP EV engine in a go-kart is a personal favorite). Plus there's tons more to do besides just races. It looks like a deceptively simple game, it is not.

I think your best bet is emulation. I don't know how easy is it to emulate PS3, but PS2 is incredibly easy, and Gran Turismo 4 runs flawlessly that was.

I'm not really plugged into the racing scene but my buddy suggested Wreckfest. As they have workshop support, so someone may have made the tracks you're hoping for.