http://victorythegame.com/
Victory is a F2P racing MMO that's currently in Beta. It is brilliant. You need to play it.
Why?
Two main reasons:
1) The aesthetic. I normally don't care about stuff like this in a game, but this one looks awesome. The cars come in three classes. Rookie (unlocked at the start), Semi-Pro (unlocked at level 21) and Pro (unlocked at level 41). Rookie cars look like 60 era F1 cars (until people start putting mud-guards on them, that is). Think along the lines of the first DFV Lotuses. Semi-Pro cars look like something from the 70s, a couple of rear-end option even coming with a mid-70s oversized airbox. And the Pro cars look like 'modern' cars from the late 90s onwards. That is the most awesome way I've ever seen class progression represented in a game. It helps that there's a customation system so you see a few 50s Merc and Ferrari replicas going about at Rookie level. I even made this:

Yes, I do enjoy ripping off the Mazda 787. It's a Semi-Pro car, btw.
Just be careful with the editor, because you can't go back and re-edit the car's appearance once you've hit the checkmark on each decal without resetting the whole lot, which cost in-game money.
2) The physics engine. It is one of the best I've played. No arcad-ey slides here, this is a simulation engine. The car feels like it has genuine weight that's transferring around under brakes and in corners, and you can't just throw it into a corner and hope it sticks, because it won't. You will, at best, sacrfice a tonne of apex speed with your big ass slide, and at worst, be introduced to Mr. Wall on your way out. You have to drive it like an F1 car, slow down, turn in, get back on the power. There are AAA titles (Need for Speed, I'm looking in your direction) cannot touch the quality of this engine.
Collision physics are optional, with dedicated race lobbies featuring both collision disabled and collision delayed (collision detection activates halfway around the first lap to avoid a huge first corner pile up) settings. It even comes with customisable set-ups, which you will need to play with to get the best times on each track. There's huge depth in it, I was owning people with the same PI as me (see below for this) to the tune of 2 seconds a lap earlier today and still not getting near the lap records. It also has the best keyboard controls I've played since Grand Prix 4.
Drawbacks:
The player base at the moment is tiny, and the game uses a levelling system.
Put the two of these together, and you get a situation that until you reach level 20, the point at which you can max the Performance Index [PI] of your Rookie car, which is basically points you can add to improve the stats of it as you level up, you'll frequently find yourself racing against better cars. They are planning to solve this with O PI lobbies, that remove all your car's PI so everyone's equal, but they haven't been implemented yet.
The other effect is that even people at max level will still race their Rookie cars because there are hardly ever enough Semi-Pro and Pro drivers on to have a race atm, which is a shame. But that's stuff that will be sorted as the game gains attention. Hence why I'm directing you people to it.

The only other potential issue is that the servers are based in Italy, so those outside Europe may have to contend with ping/latency issues that I haven't noticed.
My IGN is 'Skrallis' if you're interested in racing with me. I'll even crack open a new 0 PI car so it'll be a fair race.