The ActiveHybrid 5 is BMW's third hybrid model – the first two being variants of the X6 sport-utility vehicle and 7 Series limousine.
However, it is the carmaker's first hybrid available in right-hand drive – hence its introduction to Singapore.
Powered by the same turbocharged 3-litre six-cylinder engine as the 535i, this German sedan has the advantage of extra help from a 54bhp electric motor and lithium-ion battery pack, together boosting the output to 340bhp and 450Nm – 34bhp and 50Nm more than what the 535i produces.
At speeds of up to 60 kmh, this hybrid can run on electric power alone – as long as there are no inclines and throttle inputs are gentle. Step harder on the go pedal and the electric motor assists the petrol engine to give the ActiveHybrid 5 strong performance. How strong? BMW quotes a 0-100 kmh timing of 5.9 seconds – exactly the same as the 535i and it feels that way.
With maximum torque available from 1,200 rpm (just above the engine's idling speed) to 5,000 rpm, there is plenty of overtaking punch on tap, making this green BMW the perfect highway tool.
The eight-speed drivetrain has another party trick. Unlike conventional automatics that employ a torque converter, the ActiveHybrid unit uses a clutch instead.
As a result, when Eco Pro – the most economical of the five driving modes – is selected via a rocker switch located next to the gear lever, the engine is able to decouple itself from the transmission, allowing the car to coast at speeds of up to 160 kmh.
The Eco Pro mode also adjusts the gear changes, throttle mapping and even the climate control to make every drop of petrol last as long as possible.
Also helping the fuel economy is the Hybrid Auto Stop-Start function, which allows the air-conditioning to run on power from the lithium-ion batteries alone when the engine is shut off.
Compared to the 535i, the ActiveHybrid 5 consumes 1 liter less for every 100 km travelled, making it the most fuel-efficient petrol model in the 5 Series line-up today.
Under most driving conditions, the change in propulsion methods is hardly discernible. Only at lower speeds is there a hint of a judder whenever the engine turns on or off. Otherwise, the only way to actually know for sure what the drivetrain is doing is to bring up, on the multifunction display, the diagram showing the hybrid system's real-time transfer of energy.
Despite weighing 190kg more than the 535i, the car strikes an excellent balance between comfort and agility. Much of this is due to BMW's Dynamic Damper Control, which is standard fit only on the ActiveHybrid 5 and range-topping V8 550i.
This clever system uses a control unit on each wheel to evaluate movements 400 times a second and adjusts the dampers accordingly. It works so well that when the front wheels encounter a pothole, information is immediately sent to the rear dampers so that sufficient cushioning is provided.
On the outside, the ActiveHybrid 5 sports a few bespoke features that differentiate it from the rest of the 5 Series family. The grille, for instance, is finished in matte silver and there are badges bearing the model name on the C-pillars and boot lid.
Also new is Bluewater, the metallic light-blue paintwork worn by our test car. Not so pretty are the 18-inch wheels with their thick, “bladed” spokes in a black-silver finish. But these were designed to slice through the air more efficiently, so all is forgiven.
Step into the cabin and it is not much different from any other 5 Series'. The interior is roomy and beautifully built, and most of the functions are controlled through the user-friendly iDrive system.
Like the exterior, the more obvious tell-tale signs of this Beemer's identity are the “ActiveHybrid 5” lettering on the door sills and the aluminum plate mounted on the centre console.
The hybrid's only significant difference from a regular 5 Series sedan is in the boot, where the capacity has been reduced by almost 150 liters, making it considerably smaller than the trunk of a 3 Series saloon. This is due to the lithium-ion battery pack located behind the rear seats.
In terms of dollars and sense, the ActiveHybrid 5 costs S$18,000 (US$14,172) less than the 535i, yet is equally quick and has a longer list of standard equipment. That it also needs fewer visits to the petrol station is the icing on the cake.