I have "I Know You Got Soul" and "Motorworld". Also have Hamster's book "What Not to Buy".
I think the next one I'd like to get is "Born to be Riled."
Here are some thoughts on them:
"I Know You Got Soul" - A bit hit-and-miss for me. All of the things he picked were
interesting, but some were a bit boring. Still continues the trend of "if it wasn't built by a Brit, it's good, but could have been SO much better if it was British" thing, which I find quite tiresome. I do like that he added fantasy elements, like the Millenium Falcon. Overall, a decent read, but didn't hold my interest 100% of the way through.
"Motorwold" - A nice companion to the series, with some extra stories not mentioned on TV, but considering how huge an adventure he had, the book could have been much, much bigger. I would say a good 85% of what's in the book you'd already know if you watched the shows, so there isn't a whole lot of new information to be found, sadly.
"What Not to Buy" - Pure comedy. A really fun book explaining Richard's view of how the cool wall should work, in a sense. There's a lot of variety in it, which is nice, and some great pictures. Again, it could be longer, but it's not exactly a coffee table book in the first place. It's a fun book that I think even a non-car lover would also appreciate.