Ciao GrandeP:
There are many examples of cars modeled 100% in MO-AI
a Ferrari,a WV Beetle,an old Citroen 2cv,Lamborghini Reventon,few concept-cars following modern lines by Raoul....so:yes we can ! :)
(Michael tends to dissuade users to model cars:he's right,in teory...in this case feel free to forget and go ahead with your idea :) )

This is about first approach:
Nurbs are more intuitive but you have less control on surfaces and details
Sub-D gives you full control on everything but require much more effort to achieve what you want


Modeling techniques:
here in MO-AI you can obtain main shape using Loft for some kind of cars,or using whole toolset mixed together..just depends by details and features
if you want to do a car "panel by panel" you need a software that gives you- 4 sides curvature continuity options-
Rhino and MOI don't have these advanced options so you should use - ALIAS-


As Michael said to you, have a try downloading trial version
play on it...watch your feedbacks...if you feel good in MOI's environment, you can start to do your car :)