Despite growing in size, the next-gen 5 Series is expected to shed some weight, with rumours indicating that the new model will tip the scales at around 100kg less than the current-generation car.
Like the next 7 Series sedan, which is expected to debut next year, the new 5 Series will be based on BMW's new "35up" platform. "35up" based vehicles will feature a large quantity of carbonfibre and aluminium, as well as high-strength steel, in their structure.
Bearing the model code G30, the next-generation 5 Series is expected to make its debut in 2016.
Rumours suggest that motivation for the new 5 Series range could start with a 1.5-litre turbocharged motor and stretch all the way through to a, probably V8-powered, M5 performance sedan.
The car that our photographers happened upon seems to be a plug-in hybrid variation, as evidenced by the second "fuel" cap in the front fender (above).
This car's drivetrain could be similar to the recently detailed, but yet-to-be-released, 3 Series plug-in hybrid. That car has a total of 183kW of power and 400Nm of torque at its disposal thanks the combined efforts of a 132kW/320Nm 2.0-litre petrol engine and a 70kW/250Nm electric motor.
In the 3 Series, this drivetrain powers the rear wheels via an eight-speed auto, and is good for an overall fuel economy rating of 2L/100km and about 35km of electric-only driving.