Dithering is actually fine if you want it consistent with Fallout 2 graphics. IMHO the main problems are:
- the car body texture is too plain. Original cars had more rust/dirt details, bumps, scratches, paint peeling off etc. The diverse details would also hide dithering to some extent.
- windows are completely black, which make it look even more plain. In the original you can see there is something inside, which give you a sense of hollow space, not just black void, which make it look like a fake car prop.
- Highwayman is definitely more metallic/shiny, although it's not the case with all Fallout 1&2 wrecks.
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As you can see 2D engine wins!
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With renders you can have as many details as you want.