The image files in the "base\graphics" folder are the individual frame images for the game's sprites. These files are simply high/true colour (no colour palette) PCX files
Each image file has the following name standard:
ImageName_XX_YY.pcx
XX is the image number.
with one leading zero (its always 2 digits, i.e. 01 or 05). For example the first car in the game could be car01_YY.pcx.
YY is the frame number.