I realize this is mainly a crashing game, but how is the actual driving physics? And can you use a wheel with it?
The sandbox style gameplay intrigues me, but I'm afraid it's gonna feel like one of those games where after 1 hour the novelty factor wears off and you don't have anything to do. It also seems like one of those games that is perpetually stuck in Early Access...
Physics are decent. Not a simulator, since it's not what the game is intended for, but it's definitely not arcade either. The developers are constantly tweaking the physics, and so far, the game feels really good. There are race tracks in the game and some missions do require racing. I would compare the physics somewhat similar to the old Driver games, or GTA 4 (kind of wobbly and mushy) but with a much more defined weight transfer, oversteer and understeer.
As for the mechanics, you can customize almost every aspect of the vehicles, to the most technical detail. Differentials, brakes, engine, tire pressure, suspension and such. It's a lot of fun actually. You can actually modify, delete or swap almost every part of the car on the spot just to see how different they feel.
Game does support wheels. I play it with my G27, and as long as the car is equipped with a manual transmission, you can even select an H-Shifter option with clutch and it will work just fine. Force Feedback is also functional, although it is a bit strong (it can be adjusted), and it will go berserk if you break your steering or suspension.
This is not a game that you will buy to spend hours on it. It's more of a novelty and an experimental thing. It is worth having, I assure you, but don't think of it as a replacement for any other racing game. My sessions are usually 20 minutes at the most, but I personally couldn't live without it. As a sandbox, there are tons of things to do. You can even program AI cars, set props and other stuff to do whatever you want.
As for the Early Access thing, this game is being constantly updated, improved and new content is added almost in a monthly basis. The developers are amazing when it comes to that, as well with listening to the fans. With the Career mode soon to be released, the game will finally go to Beta.
The games has hundreds of fully supported mods, so there is always more content to add. Just check my video above. That's actually Trial Mountain from Gran Turismo