2023 Mercedes-Benz C300d AMG Line W206

2023 Mercedes-Benz C300d AMG Line W206

The sixth generation of Mercedes’ compact executive saloon could be the best yet, thanks to a brilliant turbodiesel engine under the bonnet and a luxurious cabin stacked full of exotic features. Words Kyle Molyneux. Images Daimler AG.


Road Test – C300d Saloon

Worth the wait Read our UK first drive of the brand new C-Class Saloon in terrific 300d turbodiesel form

During last year's rather infamous UN Climate Change Conference (COP26), Mercedes-Benz was listed among 11 automotive manufacturers that had agreed to “work towards all sales of new cars and vans being zero emission globally by 2040, and by no later than 2035 in leading markets”. Other companies signed up to the declaration included Ford, General Motors, Jaguar Land Rover, Volvo and BYD Auto.

The sixth generation of Mercedes’ compact executive saloon could be the best yet, thanks to a brilliant turbodiesel engine under the bonnet and a luxurious cabin stacked full of exotic features

It doesn’t take a genius to spot the grey areas in that agreement, although Daimler CEO Ola Källenius confirmed to German newspaper Handelsblatt that “from 2025 nearly all our money is going into electromobility”, dispelling any belief that Mercedes’ parent company is going about this enormous transition in a half-hearted manner. Of course, some will argue that change in the car world isn’t happening fast enough, and others will say change doesn’t need to happen at all…

As 'normal' C-Classes go, the old C350 CDI was my favourite – until I drove this C300d

So, where does this leave cars like the brand new C-Class and engines like this 300d’s four-cylinder turbodiesel? The great news is that this 206-series generation of Merc’s compact executive already boasts electrified powertrains, and C300e and C300de plug-in hybrid models are on the way. The C’s diesel motor, the ‘OM654 M’, is part of Merc’s latest Family of Modular Engines (FAME for short) and incorporates an integrated starter-generator (ISG) between the engine and nine-speed 9G-Tronic autobox, meaning this C300d – and all other C-Classes without a plug socket – are classed as mild hybrids, so certainly haven’t been left behind in their maker’s pursuit of greener motoring.

2023 Mercedes-Benz C300d AMG Line W206 - interior

The ISG and its 48V electrical system provide a fuel-saving gliding function that sees the engine switched off on the move and restarted seamlessly when required, plus a performance-enhancing EQ boost mode that unlocks an extra 20bhp for short periods of time. The ISG can also recuperate kinetic energy and convert it to electricity to power the air conditioning compressor. Armed with Merc’s latest two-litre turbodiesel, drivers are gifted six-cylinder levels of performance and the kind of efficiency that would rival base oil burners of a few generations ago. So you still won’t get stung too badly at the refuelling station, nor will you suffer crippling costs at road tax renewal time just because you fancied owning a Mercedes that’s not an A-Class, or an electric EQ model.

The new C-Class really does feel like a class above the mainstream, as it should

Premium motoring

And the new C-Class really does feel like a class above the mainstream, as it should. The exterior design is handsome in an understated, Germanic sort of way, although even in AMG Line Premium Plus spec as pictured, which adds AMG body styling and 19-inch AMG alloys, you probably won’t need to pick up your jaw off the floor at the first time of viewing. However, what the W206 lacks in wow-factor on the outside, it more than makes up for inside and on the move.

Compared to the previous generation C-Class, which shared the same rear-wheel drive ‘MRA’ platform, this new one is significantly longer (around 110mm), as well as slightly taller and wider. That means more space in the cabin, but not a bigger boot: 455 litres versus 480 litres in the W205 saloon.

2023 Mercedes-Benz C300d AMG Line W206

Setting aside the sienna brown/black leather upholstery of our test car, what really catches your eye is the standard, 11.9-inch central display sweeping up from the divider between the front occupants. The graphics of the latest MBUX infotainment system are mind-blowing – so crisp and buttery smooth in operation as you flick from menu to menu, and the resplendent flashes of colour add to the overall sense of sophistication.

Mercedes has clearly learned its lesson from infotainment systems of just a few years ago which, with their great number of sub menus, made changing and even finding basic cabin functions unreasonably difficult. Now, controls for the radio, satellite navigation, climate control and so on are far more easily reached, and the touchscreen itself is even more responsive to your fingertips. Drivers are also treated to a 12.3-inch digital instrument cluster display as standard, with several themes to choose from depending on how you wish the whole layout to look. Sport theme’s vibrant red colour scheme and big speedo is tempting, although Classic’s lovely dial set and turquoise coloured area in the centre, which serves as a backdrop for trip readings and driving efficiency ratings, wins my vote. This area can also hold a small version of the sat nav map, should you wish. Suddenly, analogue instrument clusters seem so… last century.

Fast on its feet

I could go on and on about the new C-Class’s cabin, which feels better nailed together than its predecessor’s, but let’s talk about how the W206 drives in 300d AMG Line form. It weighs almost 1.8 tonnes, but this saloon will zip from zero to 62mph in just 5.7 seconds – a decent lick of pace in anyone’s book. Better still, the diesel engine never makes its presence too obvious, this OM654 M motor surely the most refined four-pot oil burner to emerge from Mercedes-Benz.

Armed with Merc’s latest two-litre turbodiesel, drivers are gifted six-cylinder levels of performance

Not that I thought it would be terrible, but I really didn’t expect to be so dazzled by the 300d. The engine revs with the freedom of a petrol, delivers its lovely, wholesome wave of maximum torque from 1,800 to 2,800rpm, and when you’re dialled back in cruise mode you’ll see at least mid 50s fuel economy on a good run. Mercedes-Benz wasn’t exaggerating when it said the ISG restarts the engine without a hint of vibration, either. The gliding function brings no revolution in efficiency, but it’s satisfying knowing that you’re not using more fuel than is necessary.

2023 Mercedes-Benz C300d AMG Line W206

The accompanying 9G-Tronic automatic is nearly as impressive as the diesel motor, still lacking the ultra-fast responses to paddleshift inputs that ZF transmissions achieve, but somehow going beyond the oily precision of previous gearboxes and entering the realm of surreal levels of smoothness. It is very easy to forget the car is changing gear at all, in fact.

Pitch the C-Class into your first corner and you’ll probably apply too much steering lock, such is the quickness of the rack. There’s near zero feel through the twin-spoke helm – thank the super-efficient electro-mechanical system for that – but the C-Class holds tidy lines even during very rough treatment, the AMG Line spec’s 15mm lower sports suspension with selective damping helping with that effortless composure while still offering acceptable – but not exactly mesmerising – ride comfort. Those 19-inch rims do create some road noise, but that seems to be par for the course with cars these days.

So, do I have any other gripes with the new C300d? I’m not a fan of the ‘aerodynamically optimised’ wheels, or the plasticky feel to the steering wheel controls and (immovable) seat controls on the doors. And I think the 205-series’ metal toggle control for driving mode selection feels nicer to use than the latest touch-sensitive buttons at the bottom of the cabin’s big screen, but these are minor annoyances. Yes, the autobox could be more responsive to paddle inputs, but I’d happily sacrifice that extra sense of driving engagement for this level of finesse in full auto mode. The AMG Line’s ride comfort could be improved too, without really affecting handling.

Borderline Q-car

Many will not remember the short-lived 204-series C350 CDI with its stonking three-litre V6 turbodiesel producing 261bhp and 457lb ft torque. The saloon was good for 62mph in six seconds flat and I adored it. As ‘normal’ C-Classes go, it was very possibly my favourite – until I drove this latest C300d. It’s not cheap, starting at £45,925 OTR in AMG Line, or £52,125 in Premium Plus spec as tested. However, if you are looking for a four-door saloon (or estate) dripping with luxury appointments, bundles of driving assistance systems and display screens straight out of a sci-fi novel, plus an engine that’ll excite without the financial bite, then save up a few more pounds, pass over the C220d and put your name down for one of these.

Just the facts 2023 Mercedes-Benz C300d W206

  • ENGINE OM654 1,993cc 4-cyl turbocharged
  • POWER 261bhp @ 4,200rpm
  • TORQUE 406lb ft @ 1,800-2,200rpm
  • TRANSMISSION 9-speed auto, RWD
  • WEIGHT 1,775kg
  • 0-62MPH 5.7sec
  • TOP SPEED 155mph
  • FUEL CONSUMPTION 53.3-55.4mpg
  • CO2 emissions 139g/km
  • YEARS PRODUCED 2021-2023

All figures from Mercedes-Benz; fuel consumption according to WLTP Combined

19-inch AMG alloys of Premium Plus trim line. More room in the rear; sienna brown/black trim.

Safety and assistance systems

Just some of the standard features designed to take care of occupants

  • Active Blind Spot Assist
  • Active Brake Assist with turning manoeuvre function
  • Active Lane-Keeping Assist
  • Adaptive brake lamps
  • Anti-lock braking system
  • Attention Assist
  • Electronic Stability Programme
  • Speedtronic cruise control with variable speed limiter
  • Tirefit with tyre inflation compressor Tyre pressure monitoring system
  • Windscreen wipers with rain Sensor

Four-pot diesel is very punchy in 300d specification. Handling is tidy, the steering quick in its response.

I really didn’t expect to be so dazzled by the 300d

Even base spec Cs get those big colour displays. Sport display mode; Classic shown top right. Eco, Comfort, and Sport driving modes offered. Mercedes has played it safe with this C's styling.

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