The .car File Explained

Sometimes, usually inside bundles, you come across .car files. And they look promising.

(2015/05/21) Actually, there are quite a lot of .car files lying around in OS X, if you look closer. The .car is a compiled asset catalog, basically a collection of images. The system uses it, for example, to keep its GUI imagery at hand (SystemAppearance.car, for example). Inside the spotlight bundle, you will find an assets.car, containing among others the Bing logo that Spotlight uses.

Unfortunately, the .car file format is not really documented, and it cannot be opened with Xcode although Xcode is able to generate .cars. If you look around the web, there are a few tools for peeking inside .cars, though. One of them is ThemeEngine by Alex Zielenski (download here), another one is Crunch by Pragmatic Code. Haven't tried that one yet, though.

ThemeEngine allows for easy viewing of .car files.

If you intend to do some themeing, i.e. want to manipulate the system's .car files, please make sure at least twice that you have a working backup of those files! (MacConfig)