Thanks Kadri and Hannes.
Michael - Only the license plates were properly UV mapped to be able to
use an image as texture.The rest had no UV mapping at all,just
material groups.(any material assigned to a group of faces in Wings3d
results in a model part with the according default shader inTG)
This mix of UV mapped and non UV mapped parts can cause minor
problems,though.I haven't been able to find out what exactly is causing
these problems,yet.What happens is that some of the non UVed parts
need to have Power Fractals applied in World Space just like the UV
mapped parts and other non UVed parts don't.
Matts advice:
http://www.planetside.co.uk/forums/index.php /topic,17600.msg170911.html#msg170911
As for your model it depends on what you want to achieve.
Like if you want the crevices and stuff to be visible in rather close ups
under the most lighting conditions it's probably better to have the objects
UV mapped and texture them traditionally.Or if you need AO maps to bring
out certain recesses or so.
In case you don't care about things like that it's definitely better and by far
less time consuming also to use no UV mapping at all.
The above is of course just an opinion and most likely incomplete.
Feel free to ask or contribute anyone.
Edit: I have to apologize for that not working link again.I have no idea why I can't
post working links anymore.