Our spies recorded a short clip with the next generation BMW 7-Series while undergoing some winter testing ahead of what will probably be a 2015 reveal.

The all-new 7-Series will have just about the same proportions as the current model while the design will most likely be an evolution rather than a revolution. Just like in previous spy photos, the spotted prototype appears to have a more raked windscreen and a sloping roofline while at the back there are two massive trapezoidal exhausts.

It will reportedly use a new platform which combines steel with aluminum and carbon fiber that could shave off as much as 450 lbs (204 kg) from the flagship's curb weight. Engine lineup is expected to be very generous and will likely include a V8 4.0-liter twin-turbo powering a rumored M770i xDrive which will have about 475 bhp (354 kW) and 480 lb-ft (650 Nm). This will be the range-topping version as according to our sources BMW isn't planning a fully-fledged M7.

BMW could decide to show the new 7-Series in the second half of 2015 before an early 2016 market launch.

Gallery: 2015 BMW 7-Series returns in a new spy video

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