That shape is a little altered by a subtly reworked front-end with differently sculpted headlamps and new rear light lenses, while inside there are minor enhancements including a little more chrome and a bigger sat nav/TV screen. Which is nice, but what we want to know is how it goes. In short, it's a four-door supercar, a Lambo disguised as a limo, if you like. Yet it's also spookily refined and, with ABC (Active Body Control) and the same wheel and tyre upgrade as the CL600, it handles near-500bhp with a decorum that is both fitting and astonishing.

There's a little more suppleness and roll to the S600's chassis that makes it a fraction less sharp but of course supreme comfort is higher on the S-class's list of priorities than crisp handling. Driven gently, the S600 plays the role of long-wheelbase ultra-luxo barge effortlessly, yet, if you so desire, it will despatch a twisting mountain road with disdain. The traction function of ESP (stability control) gets a bit of a workout, especially in the wet but, like a well-trained valet, you hardy notice its timely interventions.

All things considered, there probably isn't a safer car to trust with so much performance. Not only does the new flagship have all the physical and electronic safety features of the previous model, it also introduces the latest concept created by the technology boffins in Stuttgart - PRE-SAFE. I reckon one of Mercedes' frequent-flyer engineers was inspired to create it after reading the in-flight safety card for the umpteenth time; essentially it involves assuming the correct position for an emergency. PRE-ACCIDENT is perhaps a more accurate title but it wouldn't have looked as reassuring in the sales brochure.

The idea is that the car detects when an accident might be about to happen and automatically takes steps to ready its occupants for that eventuality. As you slew down the road, mid-calamity, the S-class ratchets down the seat belts and, if it's open, begins to whirr the sunroof closed and, if it's reclined, begins to elevate the passenger seat until it assumes the upright position. They haven't yet cracked the problem of extinguishing cigarettes but given time...
PRE-SAFE was demonstrated at an airstrip with a variety of manoeuvres including an emergency stop, an arm-twirling opposite-lock moment and severe understeer. Reclined in the passenger seat, gazing through the open sunroof, I felt the seat belt suddenly tighten, the seat backrest begin its move to upright and heard the sunroof shush closed. So it works. The belt tightens immediately while the seat and sunroof act no more quickly than if you pressed the button, though Mercedes says that research has shown that there's often enough time to get the moves complete before the accident happens and that even if there isn't one, any move in the right direction is beneficial. If there is no accident, the seat belts release to normal tension, which is the major difference between PRE-SAFE and pyrotechnic tensioners used in other cars.

As mentioned earlier, the S-class is already equipped with copious devices designed to stop you having an accident in the first place, including ESP and Brake Assist (which applies full braking when it thinks you're in an emergency stop), and it's the sensors for these systems that PRE-SAFE uses. There are also adaptive airbags that deploy according to the severity of the impact and also take account of occupant weight.

The one system that won't be offered to UK buyers is four-wheel drive, never before seen on S-class but which has appeared on an E-class. It's academic, anyhow, because space constraints rule it out for the V12 S600. In all but snow and ice, I'm sure the ultimate S-class does nicely without it. It's an amazing saloon in many respects and quite why you'd want to spend three times as much on a Maybach is beyond me.