You can switch between modes with a button on the dashboard, but you’ll need dainty fingers if you aren’t to end up activating a load of other functions. Dynamically, there’s a smooth, almost unctuous approach to a road in electric mode, the loudest noise up to 20 miles an hour is the big tires rumbling on the Tarmac.
At low speeds the ride is pillowy, not quite heaving over gentle bumps. On a frosty morning on Northampton’s country lanes, this is a lovely experience, as you are gently and quietly cosseted, looking over the hedges at the countryside and listening to Radio 3 on the 15-speaker Burmester stereo.
But the GLC can’t hide its mass, its huge tires or its high center of gravity. Sharp-edged potholes seem to come as a complete surprise to the tires, which thump distantly below you.
Broken edges set up a side-to-side head movement in the passengers, and if you start to drive harder, even in Sport mode, there is a loose quality to the rear suspension as it corkscrews off the top of the crests.
It isn’t dangerous, more disconcerting, especially given the low- to medium-speed refinement of the system. The steering, though accurate and well-weighted, doesn’t give much feedback of what the front wheels are up to, even if it does load up in the corners. Ventilated discs all round feel strong and the brake-pedal response is consistent, despite the intervention of the regenerative braking system.
The Telegraph verdict
Weight and price are the main factors working against the car in this plug-in specification (not to mention the overadorned appearance). For many private buyers that will send them off to other brands where this amount of money buys rather more car: the Volvo XC60 Recharge T6; Land Rover Discovery Sport P300e; BMW X3 PHEV; and Audi Q5 TFSI e, for example.
For the company-car driver with off-street parking and a home wallbox, the favorable tax treatment of the GLC 300 e and its potential fuel savings should offset the high price, though not by very much. I still quite like the GLC, but, despite the technical virtuosity shown in this plug-in model, I think I’d prefer a diesel-engined version. The price of progress here seems just a tad too high.
On test: GLC 300 e 4Matic AMG Line Premium Plus
bodystyle: five-door, five-seat family SUV
On sale: now, for deliveries in march
How much? GLC range from £51,885, £72,210 as tested
How fast? 135mph, 0-62mph in 6.7sec
How economical? 565mpg (WLTP Combined), 58mpg on test Engine and gearbox: 1,999cc, four-cylinder turbo petrol, nine-speed automatic gearbox, all-wheel drive
Engine power/torque: 201bhp @ 6,100rpm / 236lb ft @ 2,100rpm
Electric power train: 134bhp electric motor with 31.2kW lithium-ion battery
electric range: 80 miles (EAER), 62 miles on test
Maximum power/torque: 308bhp / 405lb ft
CO2 emissions: 12g/km VED: £0 first year, then £155
Warranty: 3 years/unlimited mileage Spare wheel as standard: no (not available)
Volvo XC60 Recharge T6 AWD, from £61,240