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The diesel hybrid is getting closer – the Peugeot 308 Hybrid HDi

The diesel hybrid will potentially offer the best of both worlds –
zero or low emissions in urban areas, and great fuel economy at
cruising speed. Peugeot say that its 308 Hybrid HDi is almost ready –
and it will be on display at the Frankfurt Motor Show. The good news is
that it is capable of 83 mpg in the combined cycle and emits only
90g/km of CO2. The bad news is that although it’s on show at Frankfurt,
the car won’t be launched until 2010.

The
308’s diesel hybrid system helps fuel consumption to reduce by 58% in
the Urban Drive Cycle compared to a standard 308 HDi. The demonstrator
is powered by a parallel hybrid powerplant, combined with a 6-speed
electronically controlled manual gearbox. It has a 110 bhp 1.6 HDi DPFS
diesel engine coupled with a 22 bhp electric motor providing a maximum
power output of 132 bhp, comparable to that of the 308 with the 2.0
litre HDi DPFS 136 bhp diesel engine. Fuel consumption in the combined
cycle is 83 mpg and 90g/km of CO2 or a reduction of 38% compared to an
equivalent 308 diesel HDi model.

In
addition, the engine has been designed to meet the future Euro V
directive which comes into force in 2009 and offers the possibility of
driving exclusively in electric or “ZEV” (Zero Emission Vehicle) mode
for journeys in regulated urban centres.

The
aerodynamic performance of the 308 hatchback and the use of Michelin’s
new Energy Saver tyres, which reduce rolling resistance, help to
enhance further its performance.

Compared
to the previous 307 Hybrid HDi demonstrator presented in 2006, the
focus of the development has now switched to concentrating on the
packaging of the hybrid technology into the structure of the new 308,
and to ensure its compatibility with the future Euro V emission
standards.

To ensure a competitive
purchase price, priority has been given to using as many components as
possible from current Peugeot vehicles. This has enabled the number of
specific parts associated with the hybridisation of the 308 to be
reduced by around 30% compared to the previous 307 Hybrid HDi
demonstrator.

The vehicle is started
by a normal ignition key but, unlike a conventional vehicle, this does
not start the diesel engine. Instead, by pressing the accelerator pedal
with the gearbox in automatic mode, the electric motor powers the
vehicle. The diesel engine only operates when required and is
controlled by a stop and start system. All the powertrain operating
modes are controlled by a Power Train Management Unit (PTMU) according
to the driver’s requirements.

The
driver is informed in real time of the powertrain operating mode by a
schematic diagram on the vehicle’s colour multifunction display. Other
information is also available, such as the battery charge status or the
power train operation mode.

General
dynamic performance is also comparable to a standard 308 HDi. In-gear
acceleration, however, both in town and on the open road, is improved
with the Hybrid HDi. Indeed, during in-gear acceleration, the diesel
engine is backed up by the electric motor which is able on demand to
deliver a power boost of up to 31 bhp (and 96 lb ft of torque).

The
parallel hybrid power train consists of a 1.6 litre HDi DPFS 110 bhp
diesel engine and an electric motor with a continuous output of 22 bhp
and a torque of 59 lb ft. The Power Train Management Unit (PTMU)
selects the right distribution of power from both units to meet the
requirements of the driver and minimise fuel consumption.

The
electric motor alone is responsible for starting and driving at low
speed, while only the diesel engine is used on open roads and
motorways, with both units coming into play simultaneously to provide
quicker acceleration. The system is fitted with a 6-speed
electronically controlled manual gearbox able to operate in automatic
or manual sequential mode.

To extend
the battery range, kinetic energy recovered during phases of
deceleration and braking is used to recharge the batteries. A special
button provides access to an all-electric “ZEV” Zero Emission Vehicle
mode. Operation of the diesel engine is then restricted to more
pronounced acceleration phases or high speed driving. This “ZEV” mode
provides total absence of exhaust emissions and noise pollution.

A
new generation battery pack has been developed which delivers an output
of 200 volts. It is housed in the spare wheel well and doesn’t reduce
the available boot volume. The batteries are of the Nickel Metal
Hydride (Ni-MH) type.

Managed braking
maximises the recharging of the batteries during phases of deceleration
and braking. An Intelligent control of the braking optimises the
distribution between regenerative electric braking and traditional
dissipative hydraulic braking. The braking management system gives
priority to braking efficiency over the recovery of energy.

Green-Car-Guide looks forward to seeing diesel hybrid technology on our roads as soon as possible.