A performance car doesn't magically get reliable just because you drive it slow- usually the opposite actually, you get carbon buildup issues, timing chain wear issues, etc. if a motor engineered for high RPM reliability is driven gently, or worse, lugged frequently at low RPMs.
I mentioned IMS issues elsewhere in this thread, but I think you're also being disingenuous with the Cayenne.
The Cayenne is a pretty darn impressive vehicle- a full sized SUV that handles well enough to be fun on a race track, and yet also does incredible offroad. It has a lot of engine options, and while some of the earlier high performance V8 engine options had issues, most of them are very reliable. It does pay for all of that performance and capability by being pretty complex, but it's also very well built. As the older Cayennes have become cheap, there's a big following now of people doing serious offroading in them, and the suspension, body, and interiors really hold up well to hard offroad use.
I would say Porsche engines tend to have new design flaws when they do a ground up engine redesign cycle, because they are really pushing the limits with new ideas and tech, and they get reliable again after a few years. Most other car companies pretty much avoid doing that, or doing it as often, because they aren't trying to extract as much performance.