BMW is extending its ActiveHybrid technology to the (F10) 5-Series, having already announced the model for a 2011 debut and introducing a concept 5-Series ActiveHybrid at the Geneva motor show earlier this year.

Here is a set of spy shots of BMW testing the 5-Series hybrid in and around Munich. The two prototypes spotted here are each carrying a 'Hybrid Test Vehicle' sticker at the back and are both badged as a 535i and sporting dual exhaust pipes.

That's keeping in line with what we know so far. That the ActiveHybrid architecture for the 5-Series involves the coupling of a 3.0 liter straight-six twin-turbo petrol engine producing 306 PS (225 kW) with a 54 PS (40 kW) electric motor managed by an 8-speed automatic gearbox.

According to BMW, this set-up is good for a 10 percent improvement in fuel-economy over other 5-Series models, presumably that means a little more kick and better mileage over the standard 535i.

Gallery: BMW 5-Series Hybrid spied

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