The P14, as it is known internally by McLaren, will eventually replace the 650S. It is due for arrival at the 2017 Geneva motor show.
Insurance database information for this latest development car suggests the production model will retain a 3.8-litre V8 engine like that its predecessor. At 2min 55sec into the video the car's distinctive exhaust note can be heard.
This latest sighting, near Chichester, follows an earlier sighting made by our spy photographer in southern Europe and another by Dutch website Auto Wereld.
Despite the camouflage, the design of the P14 clearly takes influence from the P1 hypercar, but the brand's McLaren logo-inspired headlights seem to be gone in favour of more conventional units fitted with ultra-powerful LEDs.
The new car forms part of the British manufacturer’s commitment to launch a new model every year, including hybrid models.
The P14 will use McLaren’s carbonfibre tub - albeit in its latest form - and its power output will be extended beyond the 641bhp of the 650S.