I did read it, and there's a limited amount of information that a mechanic can discover without doing a serious amount of tear down on a car. Sure, you can make sure that it runs okay and that the transmission doesn't currently have major problems and that there aren't any major leaks, but you can't even remotely guarantee that it's going to be a reliable car, and when 50,000 dollar cars with 32 valve V8s have problems, it gets EXPENSIVE.
Making sure that the car doesn't immediately need 5,000 dollars in repairs is great and very valuable, and discerning that the car appears to be well maintained is also very valuable, but neither eliminates the possibility that he could toss a rod tomorrow and need a new 12,000 dollar engine.
It's like the people that buy beat up old 15,000 dollar Ferrari 308s because they're a Ferrari and that's what they can afford. If you can't afford to pay more than 15,000 dollars for a Ferrari, you can't afford to maintain a 15,000 dollar Ferrari. Same goes for 3800 dollar 5 series.
You talking about me, or the BMW?