The reason for filling out the logbook -- on the front page is where you put basic information about your vehicle -- so that the book is absolutely traceable to your vehicle. Things like make and model and maybe even serial number/VIN, although lots of race vehicles don't have one. Things like size and type of engine, maybe displacement and bore/stroke, perhaps even tranny ratios. Most of the stuff isn't absolutely required -- but your name, the name of the team, the vehicle identity -- that stuff for sure.
Something else that's required -- but is way too often overlooked -- is including some photos of the vehicle. They go on the inside of the front cover. There's room for four -- front, rear, and each side. Again -- we want to make sure the book is for the car or bike we're inspecting in a manner other than just noting that the LSR oval frame sticker is the correct one for the logbook.