First look: BMW heralds mild diesel-hybrid

BMW has released details of a twin-turbo diesel-electric hybrid concept car it will present at the Geneva motor show next week.

Awkwardly described as the “Vision EfficientDynamics”, the vehicle is based on the X5 SUV and is claimed to be the world’s first all-aluminium diesel with a specific output of more than 100hp.

Using a “mild” hybrid rather than the two-mode system developed in collaboration with Mercedes-Benz, Chrysler and General Motors, the vehicle combines a generator with a 2.0-litre four-cylinder diesel engine.

The latter features BMW’s Variable Twin Turbo technology, third-generation common-rail fuel-injection and all-aluminium gearbox housing.

It develops 150kW and 400Nm (between 2000rpm and 2250rpm), while the generator produces 15kW and 210Nm under acceleration.

BMW claims the vehicle – which drives through an eight-speed ZF automatic transmission that is said to be ready for mass production – can accelerate from 0-100km/h in 8.9 seconds, returns fuel consumption of 6.5L/100km and emits 172g/km of CO2.

According to the German manufacturer, the generator is powered directly by the engine and electrical energy is produced by regenerative braking “with a unique degree of efficiency without impairing the drive torque of the engine”.

The generator is flange-mounted directly onto the gearbox, which BMW claims allows for a more compact design and “sound arrangement” of the hybrid components. The alternator is also integrated into the crankcase rather than conventionally driven from the front of the engine.

A “high-performance, package-appropriate” lithium-ion battery pack is integrated into the luggage compartment to store the power generated.

As well as enabling optimum use of regenerative braking, BMW claims the lithium-ion batteries also “create opportunities” to power such functions as the air-conditioning, electric coolant pump and electric power steering system.

For these functions, a 120-volt vehicle power system was designed and runs in parallel with the conventional 12-volt system.

The power harnessed by the batteries is also supplemented by roof-mounted photovoltaic solar panels, measuring 1.0 metre square.

The energy generated can either be used immediately or stored for later use. Interestingly, the power created in this clean way can be used to pre-heat the diesel fuel, considerably shortening the less efficient warm-up phase.

The concept also features aerodynamically efficient 19-inch light-alloy wheels with reduced ventilation, which are said to further reduce fuel consumption.

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