The best car in the world? That'll very probably be the Mercedes-Benz S350 BlueTEC. Or at least the new S-Class in general.

But what does that actually mean here in 2014? The fastest? The most efficient? The techiest? Hold those thoughts. First, know this: the new S-class brings together unprecedented levels of technology, luxury and efficiency, and somehow still manages to be more than the sum of its parts.

This is a car that can drive autonomously, spot humans with night vision cameras and detect and avoid collisions.

All the while, it will also massage all four main seat occupants, pummel them acoustically with a preposterously powerful 1,540W audio system and even perfume the air.

Oh yeah, and this long-wheelbase lump of luxury will do nearly 60mpg on the motorway. Remarkable.

Mercedes S-Class
This is what luxury looks like

Don't mess with the best

But back to that best-car-in-the-world accolade. There was once a time when it meant oh so much to the likes of Rolls Royce, Mercedes-Benz, Jaguar and other premium brands to be the best.

More recently, the general standards of the big brands – dynamically at least – has become so good that the question of the world's best car seemed a bit moot. They were all so damn excellent, your choice was rather more, well, sartorial. A question of style more than substance.

But the arrival of the new Mercedes-Benz S-Class has us wondering whether that best-on-the-planet conundrum is worth revisting. The new S-Class raises the bar in so many ways, maybe being best is relevant again.

Self-driving S-Class

To explain why, let's start with the tech and driver aids in particular.

Mercedes recently demoed a prototype S-Class completing a 62-mile route on public roads in Germany entirely autonomously.

Now, there's quite a bit of debate regards the desirability of driverless cars. We think there's an overwhelming argument in favour.

But there's also a debate over whether it's technologically feasible. Well, folks, get this. The new S-Class can drive itself.

OK, only in a very narrow set of circumstances. Mercedes might not actually be comfortable with us characterising the S-Class as being capable of complete autonomy, even for a moment.

But that's exactly what happens on clearly marked multi-lane roads. That's thanks to the addition of Steering Assist to Mercedes' Distronic Plus cruise control system.

Distronic Plus can already accelerate and brake according to the speed and proximity of other vehicles. But the Steering Assist system can also keep the car centred in-lane, including steering through gentle bends.

Mercedes S-Class
We welcome our new robo-driving overlords

The laying of hands

You need to keep your hands on the wheel for the system to function. But that's all you need to do. We travelled a section of M5 motorway road works with no input whatsoever from the driver. The car controlled everything – speed, trajectory, the works.

If there is a down side to this technology it's that from the driver's perspective, it's not clear when and why it's available. It uses stereo cameras to detect lane markings but can also 'follow' the car in front when markings are unavailable.

But in our experience, the system was somewhat mercurial. Whether it woke up and started steering didn't seem to depend on the clarity of the road markings. Despite that, when it's functioning, you know you're experiencing the future.

Mercedes S-Class
Panoramic 360-degree cameras handy when parking 5-metre beast

Night vision

Anyway, the new S-Class has a veritable panapoly of sensors and driver aids. Far too many for us to cover them all. But one really intriguing feature is the night vision camera that uses an infrared camera to generate a picture of the road ahead in the driver's instruments.

What's really clever is its ability to accurately detect pedestriations and highlight them in a red box. The system works super fast and super accurately. But again, there's a problem. We don't think it's terribly practical and perhaps not even safe to look down at that screen as you drive.

What we really need is the same sensor system but relayed to the driver via a head-up display that actually highlights pedestrians as you see them through the windscreen. If anyone can do it, Mercedes can.

Mercedes S-Class
Unfortunately not taken at night, but you get the idea