Hi @oscarcorripio,
thank you very much for your tips. I have generated the volume of the basemeshbox wihout the car body but did not load it up to my simscale account for the reason I tested a little bit with stl - files which is much better with this complexity than to use step - data. Simscale runs normaly, no frozen browser etc. For the first it is good. Now I have the challenge to cut the stl for surface refinement zones and turning walls.
Additionaly I must change to free subscription for the reason my CPU hours are empty. But with stl - file it is no problem to share it in public zone for the reason there are no generic data.
Now I must wait to try to generate a mesh with the new geometry. 
Thanks and a nice weekend I wish for you
Jens