Had fun with Sports Car Designer software, How to get into 3D sketching?

[Big time]

I had great fun with 2D Sports Car Designer Software
http://www.sportscardesigner.com/

Now, How can do I get into 3d SKETCHING?
Only sketching for now, no 3D design yet

I just installed Car Sketch Tool
Car Sketch Tool
And I'm learning a bit from some tutorials.

I'm considering making a basic 3D design in Google Sketchup placing several basic components like tires, engine and maybe driver.
Then rotating it to get a nice perspective view to use it as a template and start from there.

Any advice?
tnx

[092326001]

Maybe look for some free student/trial version of professional 3d modelling software?

Not sure about sports cars, but iirc KTM used pro/engineer to design their sport bikes.