.jpk and .joe export with Blender 2.61

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What's the best track editor version ? there is 3 versions here...

I guess you are using a recent vdrift release, then the most recent one.

How do you assign asphalt, kerbs, grass, sand and wall propreties on a track ?

Assign the objects to the related surface groups. Create surface-x groups if required(ctrl+g).

You can also just import a vdrift track(jpk) into blender to get a better idea. There should be groups matching the surfaces in the surfaces.txt of the imported track.