Surfaces are not smooth enough

Hey Guys!

At first – i hopeyou understand what am i witing, i am not a native english speaker.

The Model itself was Created in Blender, so i think it should work here in this forum.

So, the problem is maybe just to simplefor the most of you, but i dont find any solution for this. I´vechanged a template for 3D Printing of a Taurus 1216 to fit anotherscale and less printet details. The original model is just fine(1:87), but the bigger model (1:32) is a bit screwed up in some partsof the model itself.

The problem is that on the curved flatpart of the frontend of the roof, you can clearly see some kind ofstairs or just to less Polygons to get a smooth surface.

Firstpicture: You can clearly see it on the headlight and the roof on theright side: (Blender)
http://abload.de/img/detail2c9kq5.png(German Pichoster)

Here is another picture with GoogleSketchUp. Here you can see that the upper right corner is smoothenedby just taking away the lines, but this doesnthelp.

I´vetried to fiy the issue by myself, but it doesnt work out well –something with rendering more Polygons and Quadrants into themodel:

Atthe moment i am working with Blender, SketchUp, Cura and a few other3D-Printing tools. I think Blender is the only tool that can fix the problem.

So, does anyone know what i can do to geta smoother surface on the .stp file?

Best regards,
Woozysheep

Add a subdivision modifier to that part of the model. And setting the shading to smooth instead of flat.