The Great Big Book of Mighty Machines is actually a collection of several individual books, like the Tractors book pictured below. It is over 100 pages and includes Bikes, Cars, Trains, Tractors, Fire Trucks, Dump Trucks and Monster Trucks. Each individual book in the collection has a border of a different color, which can then be matched to the glossaries in the back. The index covers the entire book.
Each book opens with a simple explanation of the vehicle and how it works, then moves on to different types of vehicles and how they are used. There are additional facts scattered throughout the books and each volume ends with simple activities, mostly identifying pictures and writing prompts.
The writing...these are the machine books I have been looking for my whole life. I am swoony over their tractor descriptions. Seriously. The language is simple enough to read aloud in storytime or to a small machine-obsessed child, but it includes a lot of facts and information. Interesting enough and well-written enough that it's not a bore to read, but using simple vocabulary that beginning readers could tackle with a little help. These books are amazing.
Verdict: Several of the individual titles are still in print and I am planning to purchase both the collected volume and the individual books. I heartily recommend you do the same. It's going to be a happy day when I weed our outdated machine books and replace them with these marvelous volumes.