3D Textures

First off my apologies. This is going to sound like the most noob question in the world. But how do you do 3D textures in SL. During my travels I have seen what appear to be angled textures giving cars (for example) the curves you could not normally get with just prims. Could one of y'all point me to a tutorial or post here that'll shed some light on how to do that?

It's mostly done by creating textures that have the desired light and shadow effects, and applying them to flat or curved prims. For example I saw a pink sports car a while back that looked like it must be terribly primmy. But in fact in simply had a simply-curved hood and flat sides that were alpha-mapped. Couldn't tell unless you saw it partially rezzed, or selected it in edit mode and counted prims.

I do 3D window frame textures that look like very primmy multi-pane windows, but are only a single prim. I make them in DAZ|Studio, where I can set the lighting angles and other factors as I want them, and then I render "snapshots" from specific positions to get a distortion-free texture. Then I modify that in Photoshop to get the alpha masking I want and to do clean-up work.

A car would be similar. Model it in a 3D app, light it, and render from the desired angles.