Mercedes-Benz E Class

Why would you develop a powertrain that partly uses electric power, then hobble it with a thirsty petrol engine whenever that battery energy runs out? That's just what virtually every plug-in hybrid model on the market does, almost all brands linking battery power to a petrol combustion engine.

Only Mercedes ever also offered customers an alternative; PHEV models with diesel power. As an environmental solution, you might think this to be either a contradiction in terms or a rather clever idea, depending on which side of the current global warming zeitgeist you happen to sit.

If you consider it a clever idea and you're browsing in the full-sized Executive segment for a premium badged saloon or estate of this type from the 2020-2023 period, you'll want to consider this model, the Mercedes E300 de EQ Power. The 'W213'-series E-Class range had been launched in 2016, with E300 de plug-in model's powertrain added to the range after launch.

Here, we're looking at the post-'20-era facelift version of that model, which sold (alongside an E300e petrol plug-in model) until a new generation MK6 E-Class design arrived in mid-2023.

There are no outward giveaways as to this model's plug-in status, unless you happen to notice the badging or the extra filler flap.

It was part of a 'W213'-series E-Class Saloon and Estate range that back in 2020 had recently been significantly updated. The swept-back power domed bonnet flows down into a grille that as part of this update was turned upside down, becoming wider at the bottom than the top.

In profile, this remained a stylish piece of design, the powerfully-extended silhouette characterised by short overhangs, a long wheelbase, large wheels and taut, well-defined flanks.

The alternative Estate version adds 10mm of length. At the rear, as part of the W213 facelift, the saloon body shape gained much wider, now horizontally-orientated LED tail lamps that got segmented by a restyled boot lid and sat above a revised bumper. Inside, the main change with this revised version of the W213-series model, apart from a revised steering wheel, lay with the adoption of the brand's MBUX operating system for its so-called 'Widescreen Cockpit' dash design.

This became an intuitive set-up with artificial intelligence capabilities able to predict what the user would like to do next.

It uses two 12.3-inch displays, one for the instrument cluster and one for the central MBUX infotainment screen, blended beneath a shared glass cover. As always with an E-Class, everything does of course all feel suitably premium, with leather upholstery and heated front seats being standard fit on all variants.

There's also a lovely 64-colour ambient lighting system, with LED strips along the bottom of the fascia, on the door cards and along the side of the centre console that give the cabin a very special feel after dark. In the rear, passenger space is generous.

If the front passengers have their seats at the lowest setting, you might find room for your feet slightly limited, but otherwise the rear foot wells are big and broad.

There's an issue with boot space though, which falls substantially over what you'd get from an ordinary W213 combustion model, thanks to the need to house the PHEV system battery beneath the floor.

The saloon model's trunk space falls from 540-litres to just 370-litres (less than you'd get in a Golf), though you can fold forward the 40:20:40-split rear backrest to extend it.

The Estate model's usual 640-litres falls to 480-litres (1,660-litres with the seats folded).

Please contact us for an exact up-to-date valuation.

Most E-Class (W213-series) owners in our survey were satisfied, but inevitably, there were some who'd experienced problems.

We came across a few owners who'd experienced failed NOx sensors - there are two that are a part of the selective catalytic reduction system.

The cause is usually extreme exhaust heat and replacing the sensors isn't cheap.

And we've heard it reported that the body paint is rather thin and sensitive, so scratches and spots are common.

Check the paintwork thoroughly. Some owners have reported failing LED light bulbs that illuminate the floor under the side door mirrors.

And if the car you're looking at has air suspension, we understand that the relay for the AIRMATIC system is prone to failure - that relay can get stuck in the off position, meaning that the compressor won't engage and the suspension won't drop the car towards the ground.

Otherwise, it's the usual things here; interior trim and electrical issues were the most commonly afflicted things that came up.

Check for uneven panel gaps and paint flaws.

Inspect the electrics and the air conditioning functionality - it should blow our really chilled air.

As usual, insist on a fully stamped-up service history.

(approx based on a 2021 E300 de - Ex Vat) An air filter is around £26.

An oil filter is around £13.

A fuel filter is around £36.

Front brake pads sit in the £42-£84 bracket for a set (for rears it's around £63).

Front brake discs cost in the £112-£127 bracket.

Rear brake discs can cost in the £146 bracket.

A set of wiper blades is around £42.

The first thing that'll probably strike you with an E300 de EQ Power is how refined it is.

Actually, there's virtually no sound at all from start off because, providing there's sufficient charge in the 13.5kWh battery, initial forward motion will always be battery-powered.

And providing the lithium-ion cells are fully charged up, it'll stay that way for between 31 to 34 miles, depending on the body style you choose. But it's when the battery charge runs out that the advantages of this model's rather unique diesel installation start to shine through.

Every other non-Mercedes plug-in hybrid model on the market reverts to a thirsty petrol engine at this point, tasked with lugging around a substantial PHEV powertrain.

And it is substantial; this Merc tips the scales at around 1.9-tonnes as a result.

In this case though, combustion power is metered out by a far more frugal 2.0-litre diesel (with 194hp and 400Nm of pulling power, borrowed from the ordinary E220d).

When you combine this with an electric motor generating 122hp and 440Nm of torque, the result is not only more frugal economy but a far more impressive slug of pulling power than a petrol PHEV could ever manage; this E300 de makes 62mph from rest in just 5.9s.

There are two ways of looking at this car.

If you think diesel engines are amongst the planet's greatest evils and you dismiss plug-in hybrids as fake electric cars, then you'll dismiss the concept of combining the two things as an awful idea.

We see it rather differently.

An E300 de EQ Power model, in our view, unlocks the potential of both power sources, its powertrain ensuring that the battery drive system's efficiency efforts aren't immediately undone by a thirsty petrol engine when the all-electric drive runs out.

And this package makes particularly attractive sense as part of this facelifted 2020-2023-era W213-series E-Class model. It's estimated that a large proportion of PHEV drivers hardly ever bother to regularly plug their cars in.

Here though, even these lazy owners can enjoy frugal motoring - with the potential for much more.