What's the best method for exporting/saving from Catia/Smarteam?

[theAVator]

What's the best method for exporting/saving from Catia/Smarteam for import into KS5?

I work with large/complex heavy duty commercial vehicle models, and i use KS to create realistic renderings that are used in technical training. I experimented with saving a single CGR of a vehicle, groups of CGRs per vehicle, STP files, saving the Catpart/catproduct - all with mixed results. Is there a suggested method or does anyone have a proven method that has worked "great" or even "adequately" every time?

Is there a best way preserve the hierarchy or gatherings? Preferably without having to go one-by-one and opening/saving out each grouping on its own and then importing each one-by-one into KS...