Okay, while I do have a basic understanding of engines and how they work thanks to my dad being a mechanic when I was a kid and being encouraged to look under car hoods with him (a practice that continues even today), I did not realise how many different types of engines there were and how complicated they could get. Once again, despite the book being well written, I kept getting lost and it was only thanks to the frequent and well labelled illustrations and diagrams that I managed to maintain a vague understanding of how they worked.