BMW’s head of development, Dr Herbert
Diess, explains why challenging ‘i’-car technologies will be central to an
expanding product range – and why fuel cell vehicles could become mainstream
products in certain regions.
BMW is riding high on a wave of range
renewal and expansion. The company sold a record 1.962 million cars in 2013,
and 10 new models have or will be launched in 2014, including the radical i8
plug-in sports car. The i8 promises to be like nothing else on sale in the
mainstream market, let alone a BMW showroom.
The
BMW i8 is ready to revolutionise its vehicle class. As the first sports car
with the consumption and emission values of a compact car.
The challenges of perhaps the most intense
period of vehicle development in the Munich company’s history have been
considerable, particularly for the ‘i’ models.
“It required a big effort and it was tense
last year, but once you have the drivetrains established, they are actually
easier to further develop than combustion engines are now,” says Dr Herbert
Diess, BMW board member for development. “What’s particularly challenging is
the technology that we use on the i8 because it’s a ‘street combined’ hybrid –
there are two drivetrains to synchronize, which software-wise and control-wise
was a big challenge, but that is basically done. After this year we should be
through the worst!” he laughs.
i8: A Work In Progress
BMW selected Santa Monica, California, for
the i8 launch event, partly because it is a chic locale, but also because
around 65% of i8 sales will be in the USA, and perhaps 90% of those will be to
California owners. A portion of i8 verification testing also happened just east
of there, in Death Valley, at temperatures of 40°C and above.
In conversations with Carsten Breitfeld,
head of the BMW i8 vehicle project, and Manfred Klüting, vice president of
transmission and four-wheel-drive design, one issue was clear: developing the
software strategy took the greatest priority throughout the i8 development
program, particularly the 36 months between concept approval and product
launch. In fact, this accelerated schedule for launching the i models required
further rethinking of the typical testing procedure.
At
lower speeds and in zero-emission urban areas, the i8 will run for up to 20
miles solely on electric power from a 7.2-kilowatt-hour lithium-ion battery
pack located in the tunnel between the car's two seats.
Whenever a type of hybrid system is
incorporated into a car, the testing takes on a new complexity. All initial
confirmation testing of the i8’s performance priorities took place in mules in
and around BMW’s Munich HQ. “As with any typical sporting car,” says Breitfeld,
“you must establish the acceleration goals first, and 4.4 seconds to 100km/h
was our objective for the i8.” From this acceleration target, BMW i established
absolute goals for a curb weight not to be exceeded, as well as the required
aerodynamic performance.
The initial testing around Munich involved
the first two of four prototype phases – the first to determine what needed to
be tested for the new vehicle setup and then to establish system stability –
and upward of 15 test mules. When it comes to having a performance hybrid car
that stretches its EV capabilities, engineer Breitfeld says that nearly 30%
more mileage is needed to wring out all the systems to the liking of the team
responsible for testing.
The lengthier validation phase for the i8
was run in parallel with construction of the production facility for the i
models in Leipzig, Germany. And all this was put in motion well before the
frozen i8 running prototype was shown at the Frankfurt Motor Show in September
2011.
Sometimes
it is time to leave the city. Escape the restrictions of everyday life. The BMW
i8 is an icon of progress. It combines the energizing performance of a sports
car with benchmark efficiency.
During validation testing – including the
latter two phases of finalizing full dynamic prototypes and testing under all
possible conditions – roughly 60 test cars in next-to final i8 bodywork were
used. Besides BMW’s facilities such as Miramas in southern France, testing of
all aspects took place in China, north of the Arctic Circle and in the USA.
This slightly altered testing regimen with China and other perhaps seemingly
less demanding climes was needed due to the widely varying requirements for
hybrid and EV homologation in the various markets intended for the i8. Charge
voltages vary widely, as does the infrastructure for charging stations, quick
charging and the like. There is also the challenge of making certain that in
restrictive societies, such as communist China, all the beneficial software
apps in BMW i’s ‘360° Electric’ program can deliver on their promises to
clients.
