Mercedes-Benz E-Class

The E-Class wagon was for years the quiet achiever of the Mercedes-Benz line-up in Australia. The E-Class sedan might have been the heart of Mercedes-Benz but the E-Class wagon was its soul, a car that represented the best traditions of the three-pointed star, quietly comfortable and elegantly functional, its serenity of purpose underpinned by impeccable engineering.

It was the world's best wagon.

It still is. You just can’t buy one in Australia anymore. Which is a shame, because the 2021 Mercedes-Benz E 300 de Estate is one of the most interesting E-Class wagons ever built. It’s a plug-in hybrid. With a diesel internal combustion engine.

The E 300 de Estate’s powertrain consists of a 143kW/400Nm version of Mercedes-Benz’s proven 2.0-litre OM654 turbo-diesel, with a 90kW/440Nm electric motor mounted between the engine and the nine-speed automatic transmission. Total system output is 228kW and 700Nm, sufficient to punt this 2145kg wagon from 0-100km/h in 6.0 seconds and to a top speed of 235km/h.

The e-motor is powered by a 13.5kWh battery, which Mercedes says enables the E 300 de Estate to travel up to 50km on pure electric power.

I reckon this PHEV might be one of the most sensible family cars in the business. It gives you range, without the anxiety.

Now, plug-in hybrids, as I wrote in my Wheels magazine column a few months back, often get a bad rap. The problem with PHEVs, according to the naysayers, is their electric driving range is poor compared with a proper EV, and when the battery’s done, the internal combustion engine then uses more fuel than it should by lugging around the dead weight of a slumbering EV powertrain. PHEVs are the worst of both worlds, they insist.

In theory, they’re right. But after packing a Mercedes-Benz E 300 de Estate with four adults and all their luggage then travelling from London to Cornwall and back for a week-long stay, I reckon this particular PHEV might be one of the most sensible family cars in the business. It’s an impressively efficient halfway house between a conventional internal combustion engine vehicle and a battery-electric vehicle. It gives you range, without the anxiety.

As with any good tool, though, the secret is in how you use it.

The E 300 de Estate racked up 1378km during our week away and used 61 litres of diesel fuel in the process. You read that right: A real-world fuel consumption of 4.4L/100km, achieved over a mix of 120km/h to 140km/h motorway cruising, 50km/h to 80km/h running on busy two-lane roads, and slow-speed noodling around beauty spots on the Cornish south coast.

It started the 566km run from London to Cornwall with a full tank and a 75 per cent charge in the battery that provided an indicated EV range of 27km. Left in the default Hybrid mode, the Mercedes wafted through the suburbs on pure e-power, the internal combustion engine kicking in when the battery’s charge was almost fully depleted. The little turbodiesel then did the heavy lifting for the rest of the trip.

A top-up of the 57-litre tank on arrival in Cornwall required 30.1 litres of fuel, which meant the big Benz had averaged 5.3L/100km for the trip.

The internal combustion engine would fire up just once in the next six days of driving. We were staying at a house, which meant the Mercedes could be plugged into mains electricity any time it wasn’t being used. Getting the fully depleted battery back to 100 per cent charge took between four and five hours to give what would prove a realistic range of 42km when running purely on the e-motor, perfect for the short day trips we had planned.

In all the E 300 de Estate covered about 240km on e-power during our stay in Cornwall. Indicated electricity consumption ranged from a worst of 3.4km/kWh to a best of 5.6km/kWh.

All that running was done with the hybrid powertrain control system switched from its default Hybrid mode to E-Mode, which ensures the car is only driven by the e-motor no matter how hard you press the accelerator pedal. The system also has an E-Save mode, which keeps the internal combustion engine running to preserve the battery’s state of charge, and a Charge mode that uses the engine to recharge the battery while the car is being driven. These modes are in addition to the normal quintet of Mercedes-Benz drive modes; Eco, Comfort, Sport, Sport + and Individual.

For the trip back to London, via lunch deep in the wilds of Dartmoor, the Benz started with a full battery and – as the internal combustion engine had run for only 50km since the tank had been topped up earlier in the week – a nearly full tank. Topping the car up back in the Big Smoke revealed it had consumed used just 30.9 litres of diesel over 808km for an effective average fuel consumption of 3.8L/100km.

The excellent trip computer revealed that of the 1378km the E 300 de Estate had travelled over the week, 576km – more than 40 per cent of the total distance – had been covered without the internal combustion engine in operation. And only 240km of that had been with the powertrain switched to E-Mode.

That’s because in regular Hybrid/Comfort mode, the powertrain management system would shut down the little diesel at any opportunity and allow the Mercedes to coast, or use lift-off or braking regen (the Active Brake Assist system fitted to our fully optioned test car automatically used it to slow the car when it sensed slower traffic ahead) to send charge back to the battery, which then allowed the e-motor to be used for torque fill and to power the car silently through small villages.

Of course, similar hybrid powertrain management technology is available on the five Mercedes PHEVs currently available in Australia – the A 250 e sedan and hatch, the C 300 e sedan, the E 300 e sedan, and the GLC 300 e SUV. But the E 300 de Estate’s killer app is its diesel internal combustion engine.

This Mercedes wagon plays to the strengths of both electric and diesel powertrains. Plug it in every night, and you can use E-Mode to waft smoothly and silently around the suburbs, on those runs to the supermarket, to the coffee shop and to the kids’ footy match. But when you need to head out of town and crunch the kilometres, there are few more fuel-efficient engines than a torquey little diesel running at a constant speed.

This wagon plays to the strengths of both electric and diesel powertrains. Plug it in every night, and you can use E-Mode to waft silently around the suburbs.

The E 300 de Wagon isn’t perfect. The 13.5kWh battery sits in a box across the rear load space, reducing capacity under the retractable cover by about 25 per cent. And more EV range would mean you could drive it almost all the time around town on clean and quiet electric power. The PHEV C-Class wagon, just launched in Europe, addresses both issues with a 24.5kWh battery that delivers a pure electric driving range of about 100km mounted out of the way under the rear load space.

The Mercedes-Benz 3 300 de Estate is one of the world’s best family cars. It’s smooth and quiet and roomy and comfortable, with better ride and handling than any comparably sized SUV. And that hybrid powertrain toolkit, used correctly, delivers truly outstanding efficiency.