I recently had the opportunity to drive a friend's one-owner 2002 BMW M5 under the best possible circumstances: approximately one hour before he sold it to a used car dealer.

We'll cover the sale in a second. But first, a little background on the M5, which is a four-door German super sedan known for its unequaled combination of huge, limitless engine power and huge, limitless repair bills.

The M5 made its debut sometime in the 1980s. I'm not sure exactly when, but I'd guess it happened around 1984, since they're about to make a "30th Anniversary Edition" with 600 horsepower and roughly 47 different performance settings that range from "normal" to "revving your engine like an obnoxious asshole outside a restaurant patio."

Since the original M5 came out, there have been five different versions, starting with the E28 (also known as "the one that would lose a drag race to a Mazda3") and spanning to the F10 ("the one that weighs as much as a townhouse").

Now, I think we'd all agree that each M5 has been special in its own unique way. The E60, for example, gives you that special little tingle in your wallet every time you start it up, since you're constantly aware of the fact that you might have to pawn your dishwasher to keep it running.

But most enthusiasts tend to agree there was something really special about the third-generation model, the "E39," which was sold from 2000 to 2003. And it's easy to see why: the E39 M5 looked perfect. It had the right power. It was the right size. It was solid and well-built. For many BMW fans, the E39 is the best M5 that ever existed.

My friend Keith certainly thought so, since he bought this 2002 model new in November 2001 and has owned it ever since. Yes, that's right: for approximately 12-and-a-half years, Keith has walked into his garage and climbed into this M5 every single day. It has served him faithfully for 92,000 miles. Of course, the check engine light was on for half those miles. But still: it was his check engine light.

Now, you might be wondering what my point is to all of this. ("As usual," you're thinking.) Well, there is a point, namely that I recently spent some time behind the wheel of this excellent M5. You'd know this if you followed me on Twitter, where I recently posted a photo of this car and promised a forthcoming column and video. What I didn't mention was the sale price: $11,000.

But before we cover the sale, a word on the car: sublime. This car may be only ten years old, but you really get the feeling that they don't make 'em like this anymore. The steering is heavy – a major departure from most modern cars, where you often feel like you're sitting behind a paper towel roll. The car is heavy, but not bloated. Acceleration is strong, but not excessive, and power is good, but not ridiculous. And here's the real kicker: when the turn signal goes off, it returns to its original position. This is in direct contrast to modern BMWs where the turn signal is somehow always in its original position, which needlessly complicates the otherwise simple act of putting on your turn signal. Not that it matters to BMW owners.

So now you're probably wondering: well if it's so good, then why did he sell it?! Or maybe: why did he sell it to a dealer for $9,000 under its actual value?!

Well, as you might imagine, there's a good answer to both of those questions. And it starts with my column from last week about how German reliability is the greatest myth ever sold to the American consumer.

You see, even though Keith faithfully kept up with the services, and the maintenance, and the repairs, this M5 has developed a few… problems. Let's just say he long ago passed the point of pawning his dishwasher, and for a while there he was thinking about selling his children.

Although the video gets into exactly what those issues are, the main point here is that the car needs nearly $9,000 in work to get it back into good shape – and that's not counting an impending replacement of the catalytic converters, which the dealer says will be another four figure job.

The result? After more than 12 years with one owner, this M5 has been sold to CarMax, who will inevitably dump it at auction to some used-car dealer that's looking to make a quick profit. If you run across it, I have some advice: test drive. But don't buy.

@DougDeMuro is the author of Plays With Cars. He owned an E63 AMG wagon and once tried to evade police at the Tail of the Dragon using a pontoon boat. (It didn't work.) He worked as a manager for Porsche Cars North America before quitting to become a writer, largely because it meant he no longer had to wear pants. Also, he wrote this entire bio himself in the third person.