When we first drove the new C-Class we were pretty certain that it was good enough to steal the crown from BMW’s 3 Series as the best compact executive.

Winning that title was dependent on one thing, however, the C300e plug-in hybrid. Mercedes has upped its game in this area and opted for a giant 25.4kWh battery. It has almost twice the capacity of the old one, but thanks to the car’s new platform it doesn’t eat into the available boot space.

Officially, the car can cover 62 zero-emission miles. We managed 55 in our tests. Not only does that give a benefit-in-kind rate of 8% but it also means the car is far more efficient than both its predecessor and keenest rivals in the real world. We found upwards of 80mpg to be easily achievable on longer journeys.

Charging the battery takes a little over two hours, using an 11kW charger, or about three on a normal wallbox. When the car first launched, it was equipped with DC rapid charging but this function has since been removed from UK models. It’s a shame because it made it worthwhile to charge the C Class mid-journey, taking around half an hour to replenish the battery.

The powertrain outputs 320PS in total, although the electric motor’s 130PS is enough to render the petrol engine almost unnecessary in urban driving. We were impressed at how little charge the car saps at motorway speeds, with the 55-or-so zero-emission miles still possible at higher speeds.

Open the taps and the C300e will accelerate to 62mph from rest in about six seconds. It’s quick, but the 550Nm torque output is noticeably less aggressive than the old model’s – arguably unnecessary - 700Nm output.

The C Class handles well, even with that big battery nestled in the rear. The steering is particularly quick, which makes the car feel nimble. It’s not that sporty, though. Even with its large power reserves, the car feels a tad benign in comparison to a BMW 330e.

As with all new C Class models, the C300e is equipped with an 11.9-inch central touchscreen that incorporates just about every function on board. It’s angled towards the driver and follows the gradient of the dashboard, meaning it feels as natural to use as regular switchgear.

The interior is comfortable and quiet on the move, and impressive to look at. At night the customisable ambient lighting injects a tad more excitement, but some of the plastics feel a little cheap.

In AMG Line trim, the C300e costs almost £48,655 - almost £4,000 more than the equivalent 330e. The Benefit-in-kind tax cost for drivers is more than halved, however, at £40 per month versus £89 for the BMW. Running costs are slightly higher, owing to the Merc’s steeper depreciation, but all told the C300e is a very smart choice in this segment.