My head hurts
What a brilliant game.
Seriously challenging getting the balance right

Save often, otherwise you'll need to start over from scratch, often.
Err on the side of caution rather than going for the bigger factories early, especially when you start producing your own parts. The smaller factories are best for parts early on. They also make balancing inventory easier.
Advice about going for historically successful models seems spot on; for my first model I went for a soft top small 5hp and couldn't sell it. The open top is the way to go first up.
Who knew capitalism was so hard?
