Mercedes-Benz GLC

As with the first generation GLC 300 e, a four cylinder petrol engine here is mated to an electric motor powered by a lithium-ion battery.

It's that battery that's the biggest change with this second generation GLC Plug-in, more than doubled in size from 13.5kWh to 31.2kWh, which is pretty large for a PHEV.

As is the resultant driving range figure - up to 78 miles.

To give you some perspective, the previous generation GLC 300 e only went 27 miles on battery power alone.

The equivalent C 300 e saloon has a smaller 25.4kWh battery, so only goes 68 EV miles between charges, so beyond mere practicality and fashion, there's plenty of justification for choosing the Crossover body style. If you want a Mercedes Plug-in of this size and are choosing between C-Class and GLC, there are other differences too.

The rear-driven format of the C 300 e is replaced by a 4MATIC AWD system in the GLC.

And, unlike the C-Class, the GLC Plug-in can also be had in diesel '300 de' form, if you don't mind a strike against the current zeitgeist and want even greater economy.

It's the petrol GLC 300 e variant that's our focus here though which, like its diesel counterpart, gets a 134hp electric motor to assist the 2.0-litre combustion engine up-front.

In the case of the GLC 300 e, that means a combined total output up at 308hp.

Enough, even with this car's prodigious 2,355kg kerb weight, to dispatch 62mph in 6.7s en route to 135mph. Talking of weight, there's so much of it here that Mercedes has had to fit self-levelling air suspension at the rear to better control the extra bulk of the bigger battery pack.

This damping set-up is more softly tuned than the sportier springing set-up used on more conventional GLC models, so the car feels less comfortable being thrown about - though few potential customers will want to do that anyway.

What's of more interest here is to make the most of the efficient attributes of this clever powertrain.

The car always defaults to full-electric EV mode if there's enough charge in the battery - and there usually will be because Mercedes has integrated a very effective brake regeneration system to replenish the system cells when slowing, braking or cruising.

Only when you (or the car) switch to the Hybrid drive setting does the engine come into play, with smooth, seamless acceleration via the brand's usual 9-speed auto gearbox.

There are no real styling changes to differentiate this GLC 300 e plug-in model from its conventional range stablemates, though the eagle-eyed will spot the different badgework and the addition of an extra charging flap.

As with conventional variants, there's a choice of the standard SUV body shape or a sleeker GLC Coupe body style.

Looking at the MK2 version of this model is a bit like encountering a friend who's been at a health farm for a couple of months and has emerged leaner and fitter.

Rounded edges and clean surfacing bring some of the look of the C-Class to this Crossover.

And it's sleeker than before, the drag coefficient improved by two tenths to 0.29Cd.

Plus it's 60mm longer, measuring in at 4,718mm. It's inside where existing GLC drivers will notice the biggest changes though.

The dash adopts a large central portrait screen slightly canted towards the driver.

The digital instrument display is borrowed from the C-Class too, but the GLC gets its own uniquely styled vents.

And the seats are hugely improved, with more supportive cushioning materials.

An augmented reality head-up display can be added as well. And in the back? Well if you've been persuaded to buy one of these in preference to a C-Class Estate, it's here that that decision will pay off.

This MK2 model's 15mm wheelbase increase has been put to good use in the slightly more spacious rear section of the cabin - mainly to improve legroom, not one of the previous model's strong points.

The bench slides back and forth too, which aids cargo flexibility. As before though, the PHEV powertrain exacts a few space compromises in the boot, the SUV body shape's usual 600-litre luggage capacity figure falling to just 400-litres.

With the GLC Coupe PHEV, capacity is 390-litres.

Fold the rear bench in a Plug-in GLC and the figures are 1,497-litres for the SUV and 1,335-litres for the Coupe.

Prices for this GLC 300 e 4MATIC in SUV form start from around £60,000, which is around £5,500 more than a conventional GLC 220 d mild hybrid 48V model.

Allow a premium of around £6,000 if you want the sleeker GLC Coupe body shape.

We tried this car in its ritziest 'AMG Line Premium Plus' form.

It's more likely though, that you'll be choosing between the three more affordable spec options, 'Urban Edition', 'AMG Line' or 'AMG Line Premium'.

The alternative GLC 300 de 4MATIC diesel Plug-in Hybrid model commands a £2,250 premium over the petrol version. At least the standard equipment is generous, with things like smartphone integration, wireless charging and heated front seats standard across the range.

Many GLC customers will want to look at the optional 'DIGITAL LIGHT' headlamps.

These project in front of the car onto the road surface when driving at night, with things like guidance lines, symbols and animation, plus the system's intelligent technology highlights pedestrians that you might come across with a spotlight function.

If you've extra to spend, you might also want to look at the 'Parking Package' with its 360-degree camera.

If you specify that, the cabin screen offers a 'transparent bonnet' view when you're driving off road, which shows a virtual view under the front of the vehicle, including the front wheels and the steering position.

This allows the driver to recognise obstacles like sharp stones were deep potholes at an early stage. Quite a few owners will want to add on a tow bar - and will like the clever 'Towing Route Planner' that's been added into the navigation system.

Using this, routes can be planned in the central display that are suitable for driving with a trailer, taking into account things like passage width and passage heights.

And there's an enhanced 'Trailer Manoeuvring Assistant' system that makes manoeuvring with a trailer easier, more comfortable and safer.

We've covered some of the key efficiency facts already in our driving section.

The way that an electric motor powered by a 31.2kWh battery is capable of running this car on electricity alone for up to 78 WLTP-rated miles before a 2.0-litre combustion engine chimes in.

We've found the figure to be closer to 60 miles during our test - but that's still impressive by class standards.

You can keep relatively close to that figure by proactive use of the brake regeneration gearshift paddles behind the steering wheel, which can be used to increase or decrease the amount of energy harvesting back to the battery. This GLC 300 e Plug-in variant can be had in some other markets in 55kW rapid charging form but not (as yet) here.

The UK Type 2 format charges at 11kW AC and needs two and a half hours for a 10-100% charge.

The quoted combined cycle fuel figure (470.8mpg) only goes to show how urgently we need a more real-world way of measuring PHEV fuel consumption.

Exceptional frugality is certainly possible though - expect up to 950 miles of driving range when the battery's charged and the tank's full.

The CO2 figure is a class-leading 12g/km, which equates to a super-low Benefit-in-Kind tax rating of just 6%.

It'd be 33% with a conventional GLC 220 d diesel.

That latter 6% BiK figure is shared by the alternative GLC 300 de 4MATIC diesel Plug-in version of this model, which records 565.0mpg on the combined cycle (yes, you heard that right) and 12g/km of CO2.

Insurance for the 300 e is group 47 or 48E; with the GLC 300 de, it's group 49E or 50E. What else? Well, you get a comprehensive three year warranty that has no mileage restriction (rival BMW and Audi warranties restrict you to 60,000 miles).

And this package is built upon by Mercedes' Mobilo scheme which delivers breakdown cover for up to thirty years, as long as you continue to have your car serviced at a Mercedes main dealer.

And it's worth knowing that your maintenance outlay can be kept a little in check by going for the optional Service Care package that takes care of routine maintenance, spreading the cost of regular servicing.

The industry's full of folk at present ready to write off Plug-in Hybrids.

You shouldn't listen to them.

Not only because the UK public charging infrastructure is creaking under the weight of the EV revolution.

But also because the new generation of PHEVs, typified by this GLC 300 e, make so much sense.

If only they were more affordable. Will the forthcoming full-electric version of this GLC make more sense than this? We rather doubt it.

True, the quoted fuel economy stats are ridiculously misleading, but their reality is still immense frugality, particularly the case of the alternative GLC 300 de diesel variant of this car that we might be more tempted to choose.

Either way - and particularly if someone else was paying - we'd find it hard to look beyond a Plug-in GLC of this kind if we were seeking an electrified choice in this segment.