When Mercedes builds a new S-class, the planet takes notice. It's the moment the industry's oldest and maybe most admired car manufacturer throws every atom of its expertise into re-inventing the car that has always been its heart and soul. And this time, as every time before, it has done it partly by adding new technologies that sound like science fiction.
Irrelevant to the rest of us? Nope. Technologies launched on the S-class almost always end up on the Golf about a decade later.
Many people buy an S-class not to drive but to be driven. It's one of the classic chauffeur cars. But this time around, you can be the only person in the car and still not do much of the driving. The S-class can mostly take care of speed and direction. It comes spookily close to being able to drive itself.
But aside from all the technology, the core S-class values of comfort and well-being have taken another leap forward. The cabin feels like a plushly furnished secret cave buried deep inside some mountain: it's eerily silent and thoroughly insulated from the shocks and discomforts of the world outside.
The engine - I was in the V8 - propels you down the road in astounding smoothness and silence. Suspension levelling, the epic sound system, the climate and even cabin ionisation are all monitored and controlled to the Nth degree for your absolute comfort.
The car comes in two wheelbases. The longer one has several rear-seat options, including a pair of full electric recliners with powered leg rests and inbuilt heating, cooling, massage and even armrest heating. They aren't just the usual hard-skinned orthopaedic German seats either, they're pillowy-soft and irresistibly welcoming in their embrace. Oooh-er.
You can see how much the S-class matters to Mercedes just by looking in this cabin. A BMW 7-series is mostly just a bigger better-equipped 5-series. An A8 ditto to an A6. But the S-class is different from any other Mercedes. More lavish, more special. Maybe a bit too much of an eyeful for a man of simple tastes like me, but then I'm not the target market.
And to drive? Because the new bodyshell - which uses more aluminium than before, and more high-strength steel - is considerably more rigid, there are no shudders or resonances to undermine your confidence. Most models have standard air suspension with adaptive damping. But the one I'm in, the S500L, goes a stage further.
It's got the latest version of Mercedes' active suspension, which uses not just adaptive dampers but hydraulic jacks within each air spring that can near-instantly raise or lower the spring platform, altering softness and roll stiffness at the command of the computer.
On top of that is an astounding function using stereo cameras in the windscreen. These 'see' bumps and pot-holes in the road and actually set each wheel to lift over a bump or drop into a dip at the exact moment it passes beneath. Honestly it's absolutely uncanny. They call it Magic Body Control and they're hardly exaggerating. You can go over a sleeping policeman at double the normal speed and barely feel it.
In this mode the handling is, shall we say, luxurious. The steering is accurate enough but has no feel, and the car heaves and understeers in faster bends. Fair enough, it's a luxury car and passengers come first. But if you're on your own, you can hit an S button which switches off the magic eyes, and at the same time reprograms the computer so that it causes the hydraulics to cancel all roll and understeer. It's no sports car, but it can be remarkably swift.
By the way, because of the expensive hydraulics in this system, it's one element of the S-class that won't become an option for cheaper cars any time soon.
But here's one that will. The optional driver assistance tech - or is that driver replacement? It uses a pair of cameras and three different types of radar to figure out where there are cars in front of it, and how they're moving. It reads the white lines on the road. It can spot if someone walks or cycles into its path. And then it'll accelerate, brake and even steer itself. From stop-go traffic right up to motorway speed.
It won't drive entirely autonomously - if you take your hands off the wheel for more than a few seconds, it'll demand you bring them back. And if the car in front stops entirely, you have to tap the throttle to get moving again. Anyway, you do have to keep alert, because if it gets confused and hands over to you, the situation is likely to be getting pretty critical. I provoked it by deliberately leaving my hands off the wheel, and frankly it gave me a fright or two, because it got very close to kerbs and neighbouring trucks and I didn't know whether it was going to avoid them - or not. So I grabbed control back before the experiment got messy and expensive.
The point, they say, is for the car to take some of the routine workload off you, so you can be more fresh when you need to be. I don't generally like driver assist systems, but having tried it I can kinda see what they mean. To really get the measure of it all, you'd need to do a trans-Europe road trip. And everything else about the car would be perfect for the job.
Once again Mercedes has redefined the formal German luxury barge. In all the measurables it's better than ever of course - safer, quieter, smoother and more authoritative down the road. Remember it was already the leader, or thereabouts, in those things so it's going to give its rivals an awful shock.
Maybe more important though, it's become less clinical and formal than before. It's gone quite a bit more lush.