What is it?
The plug-in hybrid version of the new Mercedes E-Class, which will be the first petrol-powered version to arrive in the UK, touching down before the end of the year. The E 350 e uses the combination of a turbocharged four-cylinder engine and an electric motor to deliver a combined peak output of 281bhp and what Mercedes predicts will be official fuel consumption of 134mpg and CO2 emissions of 49g/km.
Stop sniggering at the back, we know that achieving anything close to those numbers in the real world will mean making extensive use of the ability to recharge the 350 e’s 6.2kWh capacity battery pack using the charging port built into the rear bumper. This can replenish the pack in around an hour and a half using a high-voltage charger, or three hours via a standard domestic socket. The car’s electric-only range is a relatively modest 20 miles, but several different modes allow the assistance to be used or conserved in different ways.
These modes are Hybrid, which leaves the powertrain to its own devices; E-Mode, which operates it as a pure EV until the battery pack runs down; E-Save, which keeps the battery level constant, conserving it for use later; and Charge, which uses the engine to replenish the pack on the move. The system also communicates with the sat-nav so that when a destination is programmed it will work out the most efficient strategy over the entire route, for example, running the battery right down if the car knows it will end up at its home charging point.
The car we drove was still pre-production and Mercedes hasn’t given us a weight figure yet, but the company claims a 0-62mph time of 6.2sec and a top speed of 153mph.
What's it like?
Plug-in hybrids are getting better, but the E 350 e emphasises how they continue to suit the needs of only a small section of buyers.
Most of the driving experience is identical to the very impressive E 220 d. The hybrid has an identically nice-feeling cabin, the same dynamic options of near-autonomy and equal high-speed refinement when asked to deal with a motorway cruise.
The electron-fuelled side of the powertrain is very well suited to the urban grind. The E 350 e will try to do its trundling under electric power whenever possible, making it whisper quiet in town. It accelerates surprisingly hard before firing the petrol engine into life, with a haptic throttle making it easy to judge when this will happen – the pedal gets firm when the electric motor is giving its all.
Once running on petrol power, it doesn’t sound as refined as you would expect for a car with a 350 badge on its rump; requests for serious speed leave you in no doubt there’s a relatively small four-cylinder unit under the bonnet. But performance is strong and the throttle response is excellent, with the braking system also blending its regeneration and old-fashioned friction seamlessly.
There’s no doubting the extra mass of the electric powertrain, though. The E 350 e feels noticeably heavier and less willing to turn than the impressively lithe E 220 d, and it has more tendency to understeer as the tyres run short on grip. The standard air suspension does a good job of smoothing the ride, but can’t disguise the fact the hybrid feels chunkier than any of the other E-Class variants we drove at the launch.
The trip computer emphasised the limits of the E 350 e’s appeal. A 25-mile trip that began with the battery pack full and ended with it depleted saw the display reading 6.6 litres/100km, or 42.8mpg; numbers we would be confident the E 220 d could beat by a considerable margin without the need to find a charging point at the end of each journey.
Should I buy one?
Although Mercedes hasn’t released the E 350 e’s price yet we’re told it is likely to be higher than the impressively civilised E350 d diesel. Of course, the hybrid’s official CO2 figure will give it a compelling relevance to some company car users. Yet, although the hybrid system works well, we suspect that for most British buyers it remains an answer in search of a question.
Mercedes-Benz E-Class E 350 e AMG Line
Location: Portugal; On sale: Autumn 2016 Price £50,000 (estimated, AMG Line) Engine: 4 cyls, 1991cc, petrol, turbocharged; Power 208 bhp at 5500rpm; Torque 258lb ft; (Electric motor: 65kW/ 440Nm) Gearbox 9-spd automatic; Kerb weight tbc; Top speed 153mph; 0-62mph 6.2-sec; Economy 134mpg (est); CO2 rating & BIK tax band 49g/km (est)