In theory, a 2.0-litre diesel with only mild-hybrid assistance sounds like an outdated powertrain for a large executive saloon. BMW UK must think so: the 520d and 530d are no longer sold here. However, it doesn’t take many miles in the E220d to be reminded that, away from the tax benefits of EVs and PHEVs, diesel really suits a car like this.
You can just about hear that this is a diesel engine, but at no point is it unrefined or raucous. Whether on a cold start, while pootling through town or being run to the limiter during performance testing, this ‘OM654M’ unit quietly does its work, seemingly far away in the engine bay. Unlike some mild hybrids, you can easily disable the start-stop system, but we rarely felt the need, so quick and smooth is it to shut down and start back up.
Despite registering a planetary 1917kg on the weighbridge, and the test track being both damp and very cold, the E220d powered to 60mph in 7.2sec, which is 0.2sec quicker than the outgoing 520d. Next to many EV or hybrid options it’s nothing special (the Audi A6 50 TFSIe did it in 5.7sec), but the effortlessness impresses – and is what really counts.
First of all, it always delivers the same performance and doesn’t depend on having enough charge in the battery, like a PHEV. The engine also works well with the nine-speed automatic transmission – most of the time. The gearbox doesn’t annoy by lugging the engine like so many others, and it is quick to shift down a gear or two to make the most of the engine’s rich torque but without sending it to the redline.
Yet the gearbox is also our main target of criticism. Mostly it’s smooth, but it can be caught napping when you ask for something it wasn’t expecting. If you suddenly accelerate when you had been slowing (because the lights turned to green after all, for instance), or accelerate hard from a stop at a busy junction, the gearbox can need a moment to shift down or engage drive.
The E300e plug-in hybrid feels as quick as its official 6.4sec 0-62mph time suggests. More impressive is how the engine and electric motor work together. While some PHEVs don’t feel like they’re making all the power they’re supposed to unless you’ve got your foot to the floor, that’s not the case here. The electric motor subtly boosts the petrol engine to give efforless thrust without sending the revs soaring. The gauge cluster shows quite clearly how much throttle you can use before the engine will be forced to kick in.
The petrol engine itself is smooth and free-revving. With 127bhp of electric power, the E300e is not exactly a rapid EV, but feels swifter than that figure suggests. It’s possible to safely get up to motorway speed and stay there. While in electric mode, the shift paddles function to change the level of regenerative braking.
The software keeps a decent amount of charge in reserve, so that even when the battery is too empty for EV mode, the E300e still functions as a decent full hybrid, managing to keep the engine switched off remarkably often. Sport mode will actively recharge the battery from the engine, which is inefficient but does ensure that performance isn’t noticeably degraded.
And what of that old-school, range-topping E450d diesel? The straight-six fires up smoothly and moves the car off the mark and up to cruising speed with almost blissful ease. Though something of an anachronism in this age, it is a wonderful motor, aided by 23bhp from the 48V ISG, and a finer any-day, any-task companion for the E-Class Estate body you would hardly wish for.
Gearshifts from the nine-speed auto are better-matched to the character of this engine than the 220d somehow, and while the shift strategy is very nicely devised, even were it not it would hardly matter, such is this motor’s ability to easily drag 2.1 tonnes forward from seemingly any point in the rev range, in any gear.
The evidence of this engine’s effectiveness at low crank speeds, rather than up near the 4500rpm redline, is seen in our recorded time for 30-70mph in fourth gear. At 4.2sec it is a tenth quicker than if you’re in full kickdown. It is also, if you can believe it, two-tenths quicker than the time managed by the new AMG GT 63 super-coupe. Like we say, true Q-car appeal.
