If you are considering the purchase of a Countach, it is likely to be a used one and there is precious little information to be had on these cars. Much of Peter Dron's book consists of a light historical treatment, collected reviews and opinions from auto magazines over the years. This is useful to a degree, one does need to know characteristic data, but magazine reviews are usually pretty slim on other information that serious buyers might like to know.
True, many owners of Countachs buy them as trophies and barely break them in. Yes, there are a few racing enthusiasts. But there are also a few mundane souls who would really like to go out and drive this sort of car, rather than just invest in it, stare at it in a garage or tinker with it.
So how reliable is it day after day? Approximately how expensive is it to maintain? By 1995 this type of information should be known for each generation of the car. You won't find this in Consumer Reports either. This market ain't exactly their bailiwick. You need to talk to owners and shops.
Dron's book is useful. Much of the information that a buyer does want is in there. It could and should have been quite a bit better, but I do recommend purchasing it if you are interested in this car.