Porsche Boxster E Electric Sports Car A Hit At 2011 Michelin Challenge Bibendum

This story originally appeared at All Cars Electric

The Michelin Challenge Bibendum is an annual event run by the
French tire company aimed at promoting the development of sustainable
mobility. At this year’s event in the German capital of Berlin, Porsche rolled out its Boxster E electric car prototype, revealing a few more saucy details about its testing schedule and zero-emission future.

Porsche
is currently testing three different Boxster E prototypes as part of
the “Model Region Electro-Mobility Stuttgart” large-scale trial to
explore the everyday practicality of electric cars and how they are
used, especially in terms of driving and battery charging.

Common
to all three prototypes is a mid-engine layout, which is retained from
the production Porsche Boxster. Benefits of using this platform for
electric car testing have been its relatively low weight, packaging
attributes and low drag.

Also common is an Active Sound Design
system that provides drivers with acoustic feedback as well as alerting
pedestrians and other road users.

When it comes to the drivetrain, however, things start to change.

The
first Boxster E prototype features a twin electric motor drivetrain
with constant mesh gearboxes that act on the front and rear axles. In
this way, the Porsche Boxster E features an all-wheel drive layout
without the weight penalties of having drive shafts and differentials.
To ensure stability and traction, a central electric control unit looks
after the synchronization of the two electric motors and controls the
drive torque distribution between the axles.

Peak output comes in
at 180 kW (241 horsepower) and 398 pound-feet of torque, with maximum
engine speed coming in at 12,000 rpm. This guarantees true sports car
like performance, with the 0-62 mph dash taking just 5.5 seconds. Top
speed is limited to 124 mph, more than enough for public roads, and is
achieved without any gear change at all.

Additionally, the high
power output of the two motors offers a second advantage: it means more
recovered power is available because more energy can be recovered during
braking and thus an increase in overall efficiency.

The second and third Boxster E prototypes only feature a single motor on
the rear axle and therefore deliver half the output, 90 kW (120
horsepower) and 199 pound-feet of torque. Understandably, these models
are considerably slower, taking 9.8 seconds for the 0-62 mph dash and
with a top speed of just 93 mph.

The heart of the new Boxster E
prototypes are their lithium-iron-phosphate based traction battery,
which weighs up to 750 pounds and sits where the internal combustion
engine normally lies in the production Boxster. The overall weight of
the Boxster E prototype is just over 3,527 pounds.

Each of the
battery’s cells has a nominal voltage of 3.3 V and an individual
capacity of 20 Ah. Its energy content is 29 kWh of which approximately
26 kWh are available for use. Its maximum power output is 240 kW, or 60
kilowatts more than the all-wheel drive Boxster E draws under full load.
The battery and power unit components are connected to two water
cooling circuits.

Based on the European combined cycle, the
combined energy from 440 individual cells is good for approximately 107
miles of driving range when fitted in the rear-wheel drive prototypes.

Charging
takes approximately nine hours using a regular household power outlet
but Porsche promise that quicker times are possible using a rapid
charging function currently in the works.

Will we see the Boxster
E on sale in a few years? At the moment it’s tough to say, since
Porsche maintains that the three electric cars taking part into the
Stuttgart electric vehicle study are nothing more than rolling
test-beds.

For now we’ll just have to wait. But if you’re really
itching for an electric Porsche, there are companies like Germany’s Ruf
that are already offering electric Porsche 911 conversions for sale.