Grid is free at the Humble Store for a limited time

Codemasters’ original Grid title (sold in some regions as Race Driver: Grid) is free through the Humble Store for two days.

The game has you competing in various driving disciplines (muscle car, drifting, circuit) in a laundry list of international locations like Milan, Tokyo and San Francisco. It was released in 2008.

Head over this link and you can grab it for free.