Attach your sldprt file here.
Tutorial 6 is a toy car tutorial - but a bit different than what you are after.
You can probably get what you want with 2 extrusions - one from a profile of the top view and another (intesection - cut all outside) from side view.
Then maybe some fillets.
Think of how you will actually cut the form (I'm assuming using a band saw and then some sanded radii).
Attach your file here.