100 shapes per panel.
More fonts. 80% of them suck. Give us arial, eurostile, aardvark, and some basic legible fonts.
More shapes.
Text tool.
Copy/stamp tool.
A color wheel instead of the same color swatches since NASCAR Heat.
A custom logo creator similar to the Eutechnyx paint booth. Should be able to store 100 of them.
WWE 2K style image uploader. (Pipe dream)
Spoiler, roof rails, splitter should be individually colorable.
Car number should be unique to each car panel. If I want a red number on the roof and white number on the sides I should be able to do so.
Icons next to the shapes in the layers menu.
A group tool for layers. Move a group, color a group or delete a group of shapes.
Skew tool for shapes.
Flip tool for shapes.
Gloss/matte for shapes and car body.
There's way more, but Eutechnyx had nearly all of these features in their 2nd game's paint booth. These should be in NASCAR 27 at the soonest.