What's the best racing game? Well, it really depends of what's your catch.
Do you hate simulations? Then go alon the route of Toca RD3, GT4, etc stuff.
Do you love simulations?
If you're into rallying, nothing better (by quite a margin) than Richard Burns Rally, especially considering its mods (Snow France Mod, the 2005 WRC cars with newer and better physics parameters, the Rally Czech Plugin for online tournaments).
If you're into single-seater racing:
- you can try GPL (download the GPL2004 Demo at
www.bhmotorsports.com and see what you can get with nowadays visual modifications and enhancements). It also has two additional complete mods, one the the 1,5Litre 1965 GP cars and other with the wing-sprouted 3 litre cars of 1969.
- if you're into "modern" F1, you can try out F1C, if you can get a hand on the Ralph Hummerich 2004 and 2005 season mods (considered the best). As a cherry on the cake, you can then experience lots of mods, like the Prototype C mod (the best EVER for me), the 2003 ETCC mod or the SCC mod (2000 to 2002 LMPs and GTs basically). Unfortunately, its online capabilities fell short of the other games around here...
- you can also try rFactor, from the same guys that did the F1C game for EA. This one comes with some Formula Dodges (I think, I'm not too familiar with your racing except the ALMS), the 2005 Formula 3 cars-like and a car that closely resembles nowadays Formula1. As with F1C, this one will have many mods, though not exactly everyone understands a bit with physics (calling a "front engined" 911 as "real" is a little bit far-fetched IMHO ). Let's hope, though, for the best and that mods like ETCC or Prototype C get into rFactor.
As for online, much improved from F1C, but it still holds some strange bugs like the 1FPS bug....
).
- then there's LFS.... Hummmmm, someone said it's the most real. Well, try it for yourself (it can have the BEST physic engine, and have an UBER tire-model, but I just cannot get a grip (for lack of grip
) with it.). As a plus side, it's very good online.
- finally there is, or, at the time of this writing, there will be Netkar Pro (due to come out Monday). This, in my opinion, will be the most realistic of the bunch, seeing how good NetKar Namie was and the way Stefano Casilos (SP?) attention to details. However, I have no idea how will be the online, will it be smooth like rFactor/GTL/GPL/NR2003/LFS? No idea...
If you're into Nascar, try to get a hold of Nascar Racing 2003, as nothing comes close to it (except Nascar Racing 2002 or Nascar Racing 4... which ofcourse were made by Papyrus, the makers of all these Nascar games and GPL...and Indy500 for the Amiga
).
If you're into GT cars, there's GTR, with the same engine from F1C. Great game it is, but GTR2 is just comming out this summer.
There's also LFS, with its "GTR cars". Be aware, there's an Opel Astra Coupé wannabe with 400 plus bhp from a 2 littre turbo engine which is FRONT WHEEL DRIVE 💡 💡 .
Finally, there's GTLegends, with some GT and Touring Cars from the 60s and 70s. It has the best of rFactor (graphics and improved online) and GTR (its physics).
Live for Speed is fun simply because of the great multiplayer, and there's almost always a drift server online. 
Midnight Club 2 was fun on the PS2, and I remember there being a PC version...
. Game called cross racing championship (www.crc-game.com) little known but very good, Rfactor, GTI racing if your a fan of volkswagen, Xpand rally. 
