Haha, actually Jpjapers is right, i used couple slicers there. The second one was dedicated specifically for the rear seat, as i wanted to adjust UV mapping for better looking capping. Nevertheless, no special cap material was used.
BTW, i would like to ask devs if there's something can be done to improve capping of intersecting meshes. Currently it gives pretty messy result, as you can see from engine block and gearbox.