An exclusive, completely open speedster version of the Mercedes SLR McLaren has been spotted out testing.

The hypercar, which ends production soon, is stripped of all excess weight and features no windscreen.

Completely open to the elements, the roofless SLR is anticipated to be built in a series of only 75 cars.

Removing the roof, windscreen and equipment inside such as air conditioning is thought to have reduced the weight by around 200kg.

With reduced weight the SLR should be even quicker than its Coupé and Roadster relatives, with a top speed of over 350 km/h being rumoured.

Tiny aeroscreens are all the protection that the driver and passengers have, making helmets a necessity.

The prototype spotted testing features a double-hump rear deck and twin roll-over bars.

Prices for the super exclusive fully open hypercar are expected to be in the region of £360,000 ($720,000 CAD), Lewis Hamilton rumoured to be unveiling the car at the end of the month in Germany.