I probably have the most fun thinking up original vehicles. I usually consider details such as how to get into them and where their engines are. When you draw a real-world car, you have to obtain some references. I'd hate to have someone point out that I'm wrong. But if it's something I invented, I can have it my way.
I was one of the more talented ones at the design firm I joined, so I conducted my work pretty shrewdly. Except I wasn't a morning person, so I was quite frequently late for work. On top of that, it was a fairly big company, they were fussy about the dress code, and I got chewed out quite often.