=====.ACT=====
Adobe Color Table - Used to store 256-color palette data for RAW textures

=====.TRK=====
Truck File - Provides all information pertaining to how a truck behaves in-game. FIXME Add data from official .trk document.

=====.OPA=====

Opacity Texture - Used to provide information on what parts of the truck can be seen through, and what areas should have paint applied.

=====.RAW=====
RAW Pixel Texture - 8-bit texture data, only contains pixel values. It does not include sizing, palette data, or any attributes. Texture size is used to infer the correct sizing. NOTE: Some textures in game are hard coded to be non-square, or store multiple color channels. (ex. Loading screen/UI elements)

=====.SMF=====
Simple Model File. Plain text model format specific to the 4x4 Evolution series.

=====.SMB=====
Simple Model Binary. Binary version of above, used only on console version to reduce load times. Not supported on PC version.

=====.TIF=====
Used to store textures for [[4x4 Evolution 2]]. NOTE: it uses a non-standard TIF format that includes a 4th color channel to provide opacity texture data on trucks.