|Mercedes breaks new ground with a diesel plug-in hybrid model, which is designed to combine electric power for shorter distances up to around 25 miles with diesel efficiency for longer runs.|
|Key rival:||Volvo S90 PHEV|
|Mercedes-Benz E300de AMG Line saloon|
The drawbacks of plug-in hybrids has always included the fact that if you regularly do long trips, then the 20 or 30 miles that the battery is capable of isn’t a massive amount of use. Until now all PHEVs have been petrol-electric combinations, so a diesel has remained the logical choice for anyone doing significant and frequent mileage of more than around 60 miles between charging stops.
Mercedes is the first to bridge that gap with a diesel plug-in hybrid, which comes first to the E-Class before heading across several of the model line-up.
Called the E300de, it combines a 194hp diesel engine with a 122hp electric motor, which gives it the important figures of 41g/km and an official battery-only range of 34 miles, which translates to around 25 miles in real terms.
It comes in saloon or estate forms, with the latter costing an additional £2000, and in SE or AMG Line trim levels, and it joins the new E300e petrol-electric model.
The E-Class is easy to drive on electric-only, thanks to the dial on the dash that shows how far you can push the throttle before the car decides you want more performance and starts the 2.0-litre diesel engine to help out. It will also regenerate reasonably well, so a decent amount of zero-emission driving is possible on a trip even if the battery has started out at zero charge. The combined powertrain also gives a worthwhile performance increase, dropping the 0-62mph acceleration time to below six seconds compared with the regular un-electrified 194hp diesel’s 7.3secs. But you still don’t necessarily get that immediate surge of an all-electric car, especially as a hard push on the accelerator wakes the diesel engine.
Usefully, the charging point is in the rear bumper, so the car can be reversed into charging bays in textbook fashion, but it’s worth noting that the battery storage impacts significantly on boot space. A rectangular area takes out more than a quarter of the saloon’s luggage area, and exactly a quarter of the estate’s. That drops the saloon from 540 to 370 litres and the estate from 640 to 480. The car’s weight also goes up by over 300kg, which is a significant amount.
The downside of the PHEV is predictably price, with the battery capability adding a shade under £10,000 to the E200d, although you do also get that enhanced performance for that figure. Driver’s BIK bills will benefit, with a 40% taxpayer saving £176 a month compared with the regular diesel this year, and £255 a month next year, but it still works out at 4.3p per mile more for the plug-in from a company perspective, despite NI savings.
So fleets need to think more carefully than drivers do about deploying PHEVs, but the E-Class is the first to break new ground and offer the long-range economy of a diesel and the short-hop zero-emission driving of an electric vehicle. Which is a very welcome addition indeed.