MOI is the easiest to learn 3D modeling app I have every used. Love MOi3D. Only wish there were more youtube tutorials with audio narration on automotive modeling.
I find videos with out audio narration too difficult to follow. Perhaps it has more to do with my age (70 yrs old) and aging vision.

I have used the demo of Plasticity, but found it's ui very confusing. But it does have some interesting features.