The book is a cooperation of Debrett's - the English guide to fine manners and Vauxhall (Opel) Astra on how to behave like a lady / gentleman on the road. The pairing is a slightly odd one - one would expect a more quintessentially British brand, such as Bentley, Morgan or RR to be involved with the effort but it still works well.
You'll not read much new here - these are rules of being well behaved, unobtrusive and not obnoxious in the car in the same way one would expect to be when travelling on foot. I suppose for the reader the larger part of the value derives from the slightly quaint and funny, anachronistic way the rules are presented.
Unfortunately the people who are likely to buy the book are probably least likely to need the advice and vice versa. If everyone was to follow it to the letter, roads would be a much more pleasant place indeed, even if people would not necessarily be better drivers.
But it makes for a fun read, and I suppose, a good or obnoxious (depending on the situation and style in which it is presented) present, too, especially as it is not spoiled by too much marketing from Vauxhall's side (only a couple of shots of the new Astra and nothing more).