Following the pattern set by the BMW 5-series hybrid, Mercedes has eschewed the twin-motor, hybrid transmission-based system it jointly developed with General Motors and BMW, and effectively replaced the automatic transmission’s torque converter with an electric motor (it uses the AMG wet clutch system instead).
Where BMW uses the electric motor as an electronic supercharger, Mercedes has gone for economy with its 2.2-litre four-cylinder turbodiesel providing the motive force and headline figures of 67.3mpg in the European Combined cycle and CO² emissions of 109g/km, which means Band B £20-a-year VED.
It’s a measure of just how over-engineered Merc’s seven-speed automatic transmission is that it took no strengthening modifications to accept the electric motor’s 184lb ft of torque in addition to the diesel’s 369lb ft. The result is a top speed of 150mph, 0-62mph in 7.5sec and a range (driven gently) of more than 870 miles – that’s Land’s End to John O’Groats and back to Newcastle for a pint of Brown before closing time.
Everything, including the shoe-box-size 0.8kWh lithium-ion battery, fits under the bonnet, so there’s no loss of cabin or boot space. The electric-only range is a weedy 0.6 miles, but as Michael Weiss, the project head, says, “In our opinion, big batteries are only suitable for plug-in hybrids and even then only if they are being recharged with green electricity.”
On the road, there’s the familiar gruff beat of the four-pot oil burner, well insulated from the occupants, but audible none the less. Low rolling resistance tyres add voice to the racket and the E-class’s considerable sound deadening has its work cut out keeping the cabin noise down.
With a combined torque figure of 553lb ft when motor and engine are combined, this is a brisk car despite its kerb weight of almost two tons. That weight does inhibit the handling, however, and nose-on understeer is the main behaviour in corners. The ride is almost up to the standard of the more conventional E-class models, but the tyres pick up on road imperfections and their stiff side walls feed vibration into the frame.
The eco gadgets work well, including stop/start and the consumption displays in the speedometer, although there’s so much information being conveyed in such a small space that most drivers are likely to ignore the digital help.
Driven gently, you can achieve some amazing consumption from this car and, being a hybrid, it doesn’t fall off a cliff when you drive in urban areas, either.
Our major complaint is with the brakes, which are the bête noire of every hybrid. Like most carmakers (BMW being the exception), Mercedes has to protect the battery from overcharging by providing a digital map of deceleration for every millimetre of brake pedal travel and then modulating the friction linings and regeneration braking to achieve that. Trouble is, that leaves a wooden-feeling brake pedal. Double trouble is, in the case of the E300, the digital map ceases at about 8mph, where upon all the braking is overenthusiastically taken up by the friction linings and your passengers’ heads nod like daffodils in a breeze. You never quite get used to it.
For all its faults, however, the E300 is a creditable attempt to improve the fuel consumption of executive cars that, rather than merely paying lip service to environmental concerns, uses the benefits to increase the performance. Expect to see more cars like this soon, hopefully with better brakes.
THE FACTS Mercedes-Benz E300 BlueTEC
Price/on sale: About £2,500 on top of the cost of a E250CDI (£33,235)/ End of 2012
Tested: 2,143cc, four-cylinder turbodiesel engine, AC synchronous electric motor and lithium ion battery. Seven-speed automatic transmission, rear-wheel drive.
Power/torque: Engine: 294bhp @ 4,200rpm/ 369lb ft @ 1,600rpm. Motor: 27bhp/184lb ft
Top speed: 150mph
Acceleration: 0-62mph 7.5sec (7.8sec estate)
Fuel economy: 67.3mpg (EU Combined)
CO2 emissions: 109g/km
VED band: B (£0 first year, £20 thereafter)
Verdict: Stunning technical debut. Refinement suffers, though, and Mercedes needs to do more to solve the braking problem
Telegraph rating: Three out of five stars
