I learned in Zmodeler, almost 7 years ago, when GP4 just came out. I learned it by myself, I have never learned much by following tutorials, but's just my personal liking. It took my 6 monthes to get my first shape done, it was based on the original Bar from the game and it was a 2002 CART Lola chassis. I ended up by re-doing the most of it afterwards!
My first scratch made car with Zmod was Jordan 194, if I'm not mistaken...
When I switched to Max, I learnt once again by myself, although this time I searched some tips on the net and asked now and then to someone who already mastered Max, mainly Zeppelin101 and Erix
Max is what I use now, it's an incredibly powerful tool. But sometimes I still use Zmod for minor things or for mapping cars made with it, as McKey's 1994 cars