If you didn't like Metro Girl, you probably won't like Motor Mouth any better. Metro Girl had a very slow beginning. Motor Mouth is non-stop action . . . but it's pretty much the same gags over and over and over and over and over (you get the idea). The humor is aimed at what would thrill the average 12 year old boy (risqué talk, moderate groping, a St. Bernard knocking over people, dog elimination, and unending, silly hero worship). Unlike Metro Girl, this story is deeply steeped in NASCAR in a way that will appeal to fans of that sport. If you're not a NASCAR fan, you will think this is a two-star book.
If you liked Metro Girl, you'll probably find Motor Mouth to be a pleasant encore.
There is a plot hidden among the pratfalls and one-liners. Barney and Sam Hooker want to save one of Barney's fellow spotters from the bad guys. The rescue goes awry . . . and things go humorously downhill from there. In the course of their rescue attempts, Barney stumbles onto a plot involving a sophisticated technology. Before the story ends, bodies are piling up and women prove their superiority in smarts and toughness to men.
If you compare Barney to Stephanie Plum, you'll like this book even less than I did.
I'm not sure I'll bother to read another book in this series. Although the premise is interesting (sexy, smart, competent woman engineer attracts sexy, macho NASCAR driver) the execution generally reminds me of Ace Ventura, Pet Detective. Since Jim Carrey isn't starring in the Barney role, Motor Mouth didn't work very well for me.
My wife, who hadn't read Metro Girl, thought it was a quick, fun read. From that reaction, I suspect opinions will widely vary on this book.