.jpk and .joe export with Blender 2.61

[NaN]

how must I assign the surface as collidable ?

You have to add it to the collidable group. In 2.4 ctrl+g.
In 2.6:


To get the available groups simply export as jpk and re-import.

why I have only 1 textures appear on the track in game ? I made a track with 3dsmax an assign a multimaterial with 6 textures.

VDrift doesn't support custom materials. You have to provide a diffuse texture.
You can provide material and normal maps. Just call them xxx-misc1.png, xxx-misc2.png.
misc1: rgb: fresnel reflectance value at zero degrees, a: micro-scale roughness
misc2: rgb: normal

and blender 2.61 have any differences with version you used on video

I'll see if I find some time to create a new tutorial with 2.6