The new Ultimate Series speedster will be the lightest McLaren ever

As the lightest car in the range and powered by a version of the McLaren Senna’s 800-horsepower V8, the as-yet unnamed model focuses on on-road performance. McLaren is promising “the purest distillation” of driving pleasure in a machine that offers “an unrivalled sense of driver connection with the surrounding environment.”

The design image is all the company is showing us for now, ahead of a full debut next year. The picture shows a sleek, fully open mid-engined car without a windscreen and with prominent twin humps on the rear deck behind the two seats, in the style of a speedster. Despite speculation that it will be called the McLaren Speedster, no name has so far been confirmed.

The image hints at design cues from the 720S in the front end and profile, but with large side air intakes ahead of the rear wheels, like the Senna. The doors are low-profile versions of the familiar dihedral doors from other models.

McLaren boss Flewitt said no more than 399 examples would be built at a price between the £750,000 Senna and the £2.1m Speedtail. While the Senna fills the McLaren brief of being the most focused road-legal track car, and the Speedtail majors on ultimate straight-line speed, the third Ultimate Series model will be all about open-top exhilaration. Flewitt says the new open-cockpit roadster “will take road-focused driving pleasure to new levels.”

There are few technical details, apart from confirmation that the car will use a version of the firm’s familiar carbon-fibre safety cell. As the lightest car McLaren Automotive has made – beating the 1,188kg of the Senna GTR – it is sure to have a full carbon body as well.

All the company is saying on the powertrain is that it will be a version of the twin-turbo 4.0-litre V8 from the Senna. In its ultimate 825PS (814bhp) form in the 1,188kg track-only GTR, it delivers a power-weight ratio of 694PS/tonne.

If the new roadster matches or beats that, in a road car with no roof or windscreen, we can only see performance fireworks ahead…