A heavily camouflaged prototype of the 2017 BMW 5-Series was spotted testing next to the current model.

A heavily camouflaged prototype of the 2017 BMW 5-Series was spotted testing next to the current model.

The attached spy photos show BMW will keep just about the same proportions for the new 5-Series (G30) while the styling will most likely adopt the evolutionary route. Hiding underneath the familiar skin will be a significantly different car as the new mid-size sedan is bound to ride on the 35up platform which will make its debut later this year on the 7-Series flagship model.

This architecture switch will enable the 5-Series to shave off an estimated 220 lbs (100 kg) thanks to more aluminum and even carbon fiber. According to various reports, the weight loss will be sufficient enough to allow BMW install a tiny three-cylinder 1.5-liter turbo engine from the 2-Series Active Tourer & Gran Tourer duo, but take this rumor with a pinch of salt.

What we do know for sure is that BMW is cooking up a plug-in hybrid version that has already been caught on camera and is expected to use an adaptation of the X5 xDrive40e's hardware. In the SAV's case, the setup provides a combined output of 313 HP & 450 Nm thanks to a 2.0-liter four-cylinder turbo engine and an electric motor working together with an eight-speed Steptronic transmission and a 9 kWh lithium-ion battery.

As far as the range-topping M5 is concerned, the high-performance sedan is bound to receive an optional xDrive AWD system and an upgraded version of the V8 4.4-liter twin-turbo delivering approximately 626 HP (460 kW).

According to the latest gossip, the next generation BMW 5-Series will go on sale in June 2016 and will be followed in November 2016 by the Touring (wagon) model. Thanks to popular demand in China, the 5-Series GT will join the range in 2017.

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2017 BMW 5-Series spied testing alongside current model