Doesn't qlog.txt give you a hint on what's wrong? It should pick up on missing or misnamed texture files and shader errors, if that's where the problem stems from.
You can change the name in either Racers modeler.exe or in Zmod. Select view -> Material Editor (or just press E) and there should be a line saying <default material>, click on that, scroll to the wanted entry, change it in the name: box, hit apply, ok, then export..
i dont know what to do more to fix that dam thing changed the name of the wheel texture in DOF, messed around with shaders... the result is 0! ... the car had the rollcage with same proble (it wasent visible from outside the car, only inside) I fixed that too, and now rollcage is visible, but the wheel wont want to be seen!! xD
Dream Factory saved the day He gived me a hint to put sort_offset=-1 in the shader code! and wheel apeared behinde the windows! Now i think i'll make a better texture to it, with the same lightness for the spokes and then it'll be perfect )))