Here you can get the Vehicle Reader, source code in C++ included.
The exe is a small Direct3D application, so in order to run it, you need a basic
3D videocard, the latest DirectX runtimes from the Microsoft website, and maybe
the Microsoft dotNet Framework 2 runtimes.
Download Syndicate Wars Vehicle Reader by Marco Castrucci
Here you can find some basic info about the file format:
Download Syndicate Wars PrimVeh format description
The newer version of file format description and Vehicles Reader may be available
at author's page here:
http://www.webalice.it/mmacleod/swtemp.html
You can convert vehicles into any standard 3D graphics file format using IVCon
IVCon 3D converter information page
Vehicles in Syndicate Wars are based on Hi-Octane - race game released by Bullfrog year before. I don't know if these from Hi-octane are better.
Reworked .\QDATA files:
QDATA\PRIMVEH.OBJ