2021 Mercedes-Benz S450 L review

What is the Mercedes Benz S450 L?

This is the long-wheelbase version of the new, seventh-generation Mercedes-Benz S-Class luxury sedan, which, like its predecessors, is arguably the most advanced passenger car in the world.

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The S450 L has a 3.2m wheelbase, 110mm longer than the standard-length S450, and uses the same 3.0-litre inline six-cylinder turbocharged petrol engine that will remain the only powertrain available in the Australian S-Class range until the V8 S580 arrives later in 2021. Mercedes-Benz Australia has decided not to import diesel-powered versions due to projected low sales here.

The roomier S450 L brings additional standard accoutrements for rear-seat passengers including electrically adjustable rear seats with memory function, automatic climate control and world-first rear forward-facing airbags.

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Other new technologies standard in both versions include the second-generation MBUX (Mercedes-Benz User eXperience) infotainment system that provides personalised functions for front- and rear-seat passengers.

The S450 L we’re driving is particularly well-equipped, with optional extras including black Nappa leather upholstery ($5000), AMG Line package ($6500), Energizing Package that includes massage seats ($11,000), Rear Entertainment Package ($8700), MBUX Augmented Reality Head-Up Display ($2900), all of which takes the price to $299,000 before on roads.

What is the Mercedes-Benz S450 L like to live with?

Such is its interior space and comfort, this section could be called 'what the Mercedes Benz S450 L is like to live in'!

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All external dimensions have grown compared to its predecessor, wheelbases extended by 71mm in the regular SWB variant, and by 51mm in this stretched LWB car, where rear-seat passengers are afforded an extra 110 mm over the SWB's already generous legroom.

The first thing you notice when getting in are the solid doors with power-assisted closing to allow them to seal quietly – you close the door gently and the motors do the rest. Sitting inside, it is amazing how much outside noise is blocked thanks in part to the sound-insulating acoustic glass.

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The doors also feature flush-mounted pop-out door handles, a first for Mercedes-Benz, which extend when the driver approaches with the smart key or the outer surface of the door handle is touched, and retracted at all other times to enhance aerodynamics.

Not surprisingly, the power-operated front and rear leather seats in the world’s most popular luxury sedan are, well, pretty luxurious. As well the excellent back, side, and under-thigh support I particularly like the plush velour pillow that slides up and down the headrest to support your neck.

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The driver’s seat is so comfortable that, apart from my right foot, hands and eyes, I barely moved muscle while driving – it kinda felt like driving in bed.

If too much comfort is enough, the $11,000 Energizing Package in our review car brings seat massaging and has pre-set moods for you to select that will tailor music, ambient lighting and even aroma accordingly. It can even sync to fitness devices such as a Garmin smartwatch and will alter those settings if it detects you’re stressed or aren’t getting enough sleep.

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Rear seating is available in five different configurations – the LWB tested here has two individual seats with power adjustment, including settings that tilt the backrest and push the cushion forward like a recliner.

Behind the rear seats, the S-Class has 550 litres of cargo space with a power-opening boot lid.

As well as dishing out comfort in gold-plated spades, the S-Class interior is a technological showcase with the main exhibit being its second-generation MBUX infotainment system.

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Dominating the dashboard is a 12.8-inch portrait-orientated central OLED touchscreen, which descends like a waterfall to the centre console, and is within easy reach of the driver and front passenger.

The MBUX ‘Hey Mercedes’ voice assistant is available from every seat and can recognise and anticipate occupants' intentions using cameras that interpret head and hand movements to automatically operate functions, such as turning an interior light on when you start looking for something.

Eye-tracking technology in the cameras also recognises anyone who has registered themselves to the vehicle and adjusts their preferred settings accordingly regardless of where they sit. For the driver, this includes setting the mirror positions.

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This also makes for cool 3D effects on the 12.3-inch digital instrument cluster by continuously adjusting the image to offer the sensation of depth. There’s no practical use for this as far as we can tell – it’s just a bit cool. If you find yourself mesmerised to the point of distraction you can switch back to 2D mode.

Further individualisation of the driver display includes a choice of four graphical styles (Discreet, Sporty, Exclusive, Classic) and three modes (Navigation, Assistance, Service).

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Other standard features include Apple CarPlay and Android Auto (the former being wireless), head-up display, panoramic sunroof, 15-speaker Burmester 3D surround sound with 710W amplifier, heated and ventilated front seats, smart keyless entry and remote boot lid, fingerprint scanner and ‘AIRMATIC’ adaptive suspension.

As far as running costs go, the good news is an official combined fuel economy of 8.4L/100km, which is rather miserly considering the S-Class’s 2.15-tonne kerb weight.

Servicing intervals are every 12 months or 25,000km, which is good news for commercial S-Class operators, with the first four annual services costing $800, $1200, $1400 and $3400 respectively.

The Mercedes-Benz S-Class is covered by a five-year, unlimited-kilometre warranty for private vehicles with total mileage restricted to 200,000 kilometres for commercially operated cars.

What is the Mercedes-Benz S450 L like to drive?

At 5.2 metres long and weighing in at 2.15 tonnes before you start adding people, the S450 L seems to defy physics with its brisk performance and sharp handling.

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At its heart is the 270kW/500Nm M256 3.0-litre inline six-cylinder turbocharged engine that's carried over from the previous model and is mated to a nine-speed '9G-TRONIC’ automatic transmission with ‘4MATIC’ all-wheel-drive.

Peak power comes in at 5500rpm, with all that torque present from 1600rpm to 4500rpm, resulting in some decent shove (particularly in Sport and Sport+ driving modes).

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There is an additional 16kW and 250Nm on tap from the ‘EQ Boost’ 48-volt mild-hybrid system that helps send this giant sedan from 0 to 100km/h in just 5.1 seconds, the same as a manual Porsche Cayman.

This performance is partly due to a reduced drag coefficient compared to the previous model, resulting in a Cd (coefficient of drag) figure as low as 0.22 with the air suspension lowered in Sport+ driving mode, matching its very slippery A-Class sibling and the all-electric Porsche Taycan.

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When driving the S-Class in the more elegant manner to which its clientele is accustomed, the engine instantly responded to throttle inputs and accelerated seamlessly through the torque converter automatic transmission’s nine gears.

While the powertrain does an excellent job in shifting the S450 L’s considerable heft, its chassis and hybrid-aluminium body shell do an incredible job in containing it.

With aluminium content now exceeding 50 per cent, the new body shell is 60 kilograms lighter than the previous model’s. It also provides higher levels of crash safety and is more rigid than before, resulting in improvements to ride and handling.

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Driving through the winding roads in the foothills surrounding Victoria’s Yarra Valley, you forget you’re driving a big heavy sedan that’s longer than a Kia Carnival people mover.

The steering is well-weighted and balanced and it was incredibly simple to keep within the lines, even on the sharpest bends where I barely had to trouble the brake pedal. Body roll was also well contained even on tight turns and hairpins.

And as you’d expect with the Mercedes-Benz flagship, ride comfort is sublime on the multi-link front and rear suspension with ‘AIRMATIC’ dampers that are part of the standard equipment list.

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These adapt to the various driving modes but even in Sport and Sport+, where they stiffen for more precise handling, there is little compromise to ride comfort. No matter what driving mode you're in, it always feels like you're gliding over bumps, with next to no secondary bounce.

Ride quality is as quiet as it is smooth. The engine gives off a nice growl in the Sport driving modes but not unsociably so and the rumble from the 20-inch Pirelli P Zero run-flat tyres barely permeates the cabin.

The driving experience is also enhanced through new technology including the augmented reality function that works with satellite navigation to literally point at your turn.

It’s available as standard on the main 12.8-inch central screen but this requires you to have to look down to spot the arrows, which I found was less effective than just using the normal turn-by-turn directions on the head-up display.

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Alternatively, you can option up to a 3D head-up display ($2900) that projects the augmented reality at eye level. This makes it far easier and safer to follow the animated turn-off arrows that are virtually projected onto the road lane ahead to point out the next corner, roundabout exit or which lane to enter before the next turn or exit.

One feature I didn’t get to try was the optional rear-axle steering system that allows the back wheels to turn at angles up to 10 degrees, reducing the turning circle by 2.0 metres to less than 10.9 metres, which is about the same as an A-Class hatchback.

What about safety in the Mercedes-Benz S450 L?

Where do we start? The Mercedes-Benz S-Class has been a harbinger of new safety technology for six generations and this W223 model is no different.

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Standard on the long-wheelbase variant are world-first second-row frontal airbags. Installed in the front seats, testing has shown they reduce the likelihood of head and neck injuries for seat-belt-wearing occupants in the outboard rear seats.

This takes the number of airbags in the S450 L to 12, which also includes frontal airbags, driver's knee bag, centre airbag, full-length window bags, front and rear side bags.

The S-Class also comes with Benz’s fifth-generation Driving Assistance Package that includes a display showing what the S-Class systems are sensing and tracking at any given time via a Teslaesque digital display that shows graphical representations of any cars, trucks and even motorcycles in front of you.

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Adaptive cruise control with stop and go is also standard, along with route-based speed adaption that uses real-time traffic data to adapt to congestion on the road ahead.

Then there’s the advanced lane keep assist works at speeds up to 250km/h, evasive steering assist, driver attention monitoring, active blind-spot monitoring (that will brake to prevent an impending collision) and rear cross-traffic alert.

Its autonomous emergency braking (AEB) detects cyclists and pedestrians, can stop to avoid static objects when travelling at speeds up to 130km/h and also operates to prevent or mitigate collisions at intersections.

Cyclists are also protected by the side-exit assist system that prevents doors from being opened into approaching bikes or traffic.

The Verdict

The Mercedes-Benz S-Class has consistently been the world’s biggest-selling luxury saloon and this seventh-generation model does enough to see off key rivals such as the BMW 7 Series, Audi A8 and Lexus LS.

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The stretched S450 L, in particular, is a lot of car even for its quarter-of-a-million-dollar-plus price tag, providing an incredible mix of comfort, safety, performance and cutting-edge technology in a huge but graceful package.

What I like most about the S-Class is that it shows what is possible for a passenger car and provides a glimpse of what we can expect to see in more affordable vehicles in the near future. If this seventh-generation model is any guide, then the future is looking good.

Score: 9.5/10

PLUS: Safety, technology, luxury, performance
MINUS: Most new tech costs extra, out of reach for most

2021 Mercedes-Benz S450 L specifications

Body: 4-door, 4/5-seat sedan
Drive: AWD
Engine: 2999cc L6-cyl, 24v turbo
Power: 270kW @ 5500-6100rpm
Torque: 500Nm @ 1600-4500rpm
Mild-hybrid boost 16kW-250Nm
0-100km/h: 5.1sec (claimed)
Fuel consumption: 8.4L/100km (combined)
Weight: 2149kg
Transmission: 9-speed auto
Suspension: Front and rear multi-link/air suspension
L/W/H: 5289/1954/1503mm
Wheelbase: 3216mm
Tracks: 1660/1668mm
Brakes: Front ventilated discs / Rear discs
Tyres: Front 255/40 R20 / Rear 285/35 R20
Price: From $264,900