Sign up to WMD, the somewhat unfortunate acronym chosen for Slightly Mad's World of Mass Development platform, and you're granted access to regularly released builds of the game, which you're then free to pick apart in the official forums. That feedback then gets absorbed by Slightly Mad Studios, a simple loop that means that, when the game is eventually released, it'll be as much a product of the community as it is of the studio.
via Project Cars Preview • Eurogamer.net.
Looks like an interesting development strategy, made famous by Minecraft.