The BMW ActiveHybrid 5 isn’t an economy car. That much becomes obvious the moment you realise that its primary powerplant is the same turbocharged 3.0-litre, six-cylinder engine that drives the 535i.
And electrically assisted or not, a 300bhp petrol engine is never going to propel a 5 Series more efficiently than the four-cylinder motor you’ll find in a 520i, never mind the frugal diesel engine in BMW’s excellent 520d EfficientDynamics.
The costs of the lithium ion battery, 55bhp electric motor and high-voltage electronics that have been added to this car are simply too high to bring the ActiveHybrid 5 to market at anything less than the near-£47,000 that BMW is asking here.
A large – and thirsty – petrol engine is therefore deemed necessary to justify the car’s price and positioning.
So the ActiveHybrid 5 has to deliver more than an impressive economy figure. With that in mind, its petrol and electric motors work together to provide the car with a peak 335bhp from 5800-6400rpm and 332lb ft from 1000-5000rpm – enough, without question, to consider this car a lower-rung performance saloon.
The integration of the car’s hybrid power components is impressive. Its electric motor is located just upstream of the eight-speed ZF automatic transmission, where you’d normally find a torque converter. The driveline has two wet multi-plate clutches; one connects the gearbox to the rear wheels, while the other can disconnect the engine from the rest of the transmission below 37mph in order to allow the electric motor to drive the wheels independently.
Power for that electric motor comes from a 1.35kWh lithium ion battery mounted between the rear wheel arches. The high-voltage circuit is rated at 317 volts, and also feeds power to the car’s air conditioning. This ensures that cabin and battery cooling isn’t interrupted when the combustion engine switches off.