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
RIVALS
Mercedes-Benz 250 CDI BlueEfficiency SE Auto, from £33,235
Same engine, but subtract the electric motor, battery, £2,500, 220lb and a lot
of complexity. Expect Combined consumption of 57.6mpg, Band D 129g/km CO₂
emissions, a top speed of 150mph and 0-62mph in 7.5sec.
BMW 520d SE Auto, from £31,555
BMW’s 5-series hybrid is sold as a hot rod, so for the moment this straight
diesel auto is the closest rival to the Mercedes. It comes close, too,
offering 60.1mpg, Band D 123g/km CO₂ emissions, 0-62mph in 8.1sec and
140mph.
Mercedes-Benz E300 BlueTEC review
