I use autocad all the time as well, but I know from experience that Autocad is not really a 3d modeler, they have been getting better at it over the past few releases but ultimately it really isn't designed to be a high end modeler, they mostly just rely on 3dstudio max and rhino for that stuff. Don't get me wrong, since I know Autocad so well I find it hard to even bother learning another software but it really is quite limited once you compare it to some of the pure 3d programs.