This was originally named Carmageddon: Reincarnation. A Linux version was promised when the kickstarter reached a stretch goal of $600,000. This was passed and the announcement of the MacOS and Linux support was made.

We’ll be committing to supporting Mac and Linux, and you’ll be able to select a version to download at the same $15 and above price. And, like the DRM free version, the shipping date for these versions will be further out, towards the end of 2013.

http://archive.is/t8PWb

As of this posting, it is almost 2017 and still no version has been made available on Linux.