McLaren never built a roofless P1, but a few of them exist, five in total, and one was present during last week's 2023 Goodwood Festival of Speed in the U.K.

Known as the P1 Spider, the five roofless P1 hypercars are the creation of Lanzante, the British motorsports and engineering company that fielded the McLaren F1 GTR that won overall at the 1995 24 Hours of Le Mans, and in more recent years has been offering road-car conversions for track cars, including McLaren's P1 GTR.

Lanzante's P1 Spider made its formal debut at last year's Goodwood Festival of Speed, but at this year's event it was shown in action, driving up the famous hill climb.

The P1's carbon-fiber central tub, referred to as the MonoCage, was never designed for roofless applications, unlike the MonoCell design used in McLaren's other supercars. In addition to improving stiffness, the MonoCage also serves to guide air into the engine through an integral roof snorkel and air intake ducts, saving further weight. This meant it was a real challenge to turn the P1 into a roofless car.

To ensure that removing the roof didn't upset the performance of the car, Lanzante brought in Paul Howse, who worked on the P1, to oversee the P1 Spider project. New buttresses house air intakes that channel air to the turbochargers. The P1 Spider also gets some tweaks to its front fenders, doors, and engine cover, along with a reengineered lower chassis to maintain structural rigidity without the roof.

The P1 Spider has a manual removable roof panel rather than a retractable roof. To protect the interior, Lanzante reupholstered everything in UV-resistant leather and SuperFabric, with satin carbon fiber trim and gloss black switchgear.

The powertrain is unchanged from the stock P1. A twin-turbocharged 3.8-liter V-8 and an electric motor produce a combined 903 hp. Lanzante hasn't disclosed performance figures for the Spider, but when McLaren quoted a 2.8-second 0-62 mph time and 217-mph top speed for the coupe when it was new.

The P1 Spider is the latest in a long line of P1 derivatives from Lanzante. It previously rolled out the P1 LM, P1 GT Longtail, and P1 GTR-18—all based on the P1 GTR.