Prototypes for Mercedes-Benz’s next-generation S-Class have been spotted again.

The car is due for a reveal in September and should be available at dealers shortly after as a 2021 model.

From earlier test mules, we know the size and proportions will match up with the current model but there will be a slightly wider track, and it also looks like the hood will be lower and longer. This should give it an impressive stance.

The current S-Class, the W222, was introduced for 2014 and immediately rocketed to the top of the sales chart. The six-figure sedan racked up more than 100,000 sales in its first year and that was before the arrival of additional body styles such as the two-door cars and extra-long Maybach and Pullman.

2021 Mercedes-Benz S-Class spy shots - Photo credit: S. Baldauf/SB-Medien

2021 Mercedes-Benz S-Class spy shots - Photo credit: S. Baldauf/SB-Medien

It’s clear the new S-Class has some big shoes to fill. Luckily for it, it will adopt a new platform, in this case Mercedes’ MRA design for rear-wheel-drive cars. The current S-Class rides on an updated version of its predecessor’s architecture.

Every powertrain will be electrified, either with mild-hybrid or plug-in hybrid technology, and most engines will either be a 3.0-liter inline-6 or 4.0-liter V-8. There won't be a battery-electric version as Mercedes plans to launch the EQS to cater to EV fans. The EQS, previewed at the 2019 Frankfurt International Motor Show by the Vision EQS concept car, is also expected for the 2021 model year.

2021 Mercedes-Benz EQS prototype and Vision EQS concept

2021 Mercedes-Benz EQS prototype and Vision EQS concept

But getting back to the new S-Class, there will be much more advanced self-driving systems, including perhaps a Level 3 system. This is where the car can handle its own in certain situations, leaving the driver free to do other things. However, the driver will need to be ready to take back control at a moment's notice.

Inside, the dash will still consist of a dual-screen setup, but the secondary screen will increase dramatically in size and be mounted in a portrait orientation. Mercedes has also confirmed that buyers will have the option to add three additional screens in the rear to enable rear-seat passengers the ability to control the vehicle's infotainment and comfort features.

2021 Mercedes-Benz S-Class in-car technology

2021 Mercedes-Benz S-Class in-car technology

We also know the new S-Class will debut a second-generation version of Mercedes' MBUX user interface, feature 3D graphics in the instrument cluster, and offer a head-up display with augmented reality graphics. The HUD will virtually project upcoming turn instructions onto the road ahead. This will prove handy for showing navigation instructions like highlighting an upcoming turn.

The S-Class will have both its standard length and stretched Maybach and Maybach Pullman body styles. The short-wheelbase option sold overseas may be dropped, though. We also expect the current S-Class Coupe and Cabriolet to be phased out. A roomier next-generation SL-Class with 2+2 seating is expected to fill the void.