The evolution of the iconic Jaguar E-Type culminated in what many consider to be a true driver’s car, equal parts sporting and luxurious. The challenge of updating one of the most beautiful cars ever made was driven by demand from U.S. customers who loved the six-cylinder sports car but wanted more interior room and refinements like air conditioning. At the same time, Jaguar’s engine team were developing a more refined version of its V-12 engine that had been destined for competition use at The 24 Hours of Le Mans endurance race.

The firm’s technical director, William Heynes, pushed for the new engine to feature in an extensively redesigned E-Type. The new car, the Series III, launched in 1971, boasting the world’s only mass-production V-12 at the time, wider tires, a wider track, power steering as standard, and more powerful brakes. Jaguar is believed to have built fewer than 7,800 Series III E-Type roadsters.

Chassis no. 1S50960, offered here, is part of an even rarer sect of E-Type, having been extensively modified by New Zealand-based Jaguar specialists Beacham. With a manufacture date of 31 December 1971, it was originally built as a two-plus-two fixed-head coupe with a manual transmission, finished in white over black, and dispatched to Henlys, London on 4 February 1972, according to the accompanying Jaguar Daimler Heritage Trust certificate.

In 2013, Beacham converted the car into a roadster with a power-operated soft top and incorporated the running gear and drivetrain from a Jaguar XKR. Beneath the bonnet lies a 4.2-liter supercharged V-8 engine mated to a six-speed automatic transmission. With an advertised 400 horsepower on tap, the performance improvement is a quantum leap over that of the original E-Type.

But power is only part of the story. With five years of development, Beacham reengineered certain chassis components, devising a new subframe with custom-fabricated engine mounts to house the XKR V-8 and front suspension. The exhaust was also rerouted and a stainless-steel system with cross-balance fitted. Fully integrating modern electronic safety systems, including ABS, traction control, and air bags was a feat in and of itself.

Exterior giveaways for the impressive transformation are few—limited to the wider wheels and tires, and contemporary Jaguar mirrors and door handles. Meanwhile, the bespoke interior features modern diamond-stitched tan leather seats with black piping and all the power controls of a current Jaguar. A fully integrated center console and polished wood veneer dashboard blend classic and modern cues. Updated amenities include a power-adjustable steering wheel, seats, and side mirrors, all with memory function, as well as automatic climate control, power windows and locks, a power-operated top, and a premium sound system with navigation.

This E-Type is said to have covered around 1,200 miles since its conversion and is offered with a leather-bound Beacham driver’s handbook, tire repair kit, jack, and mallet for knocking off the wheel spinners. With perfectly integrated XKR components and numerous modern luxury and safety features, it offers exhilarating driving dynamics and refined comfort unobtainable with period components, coupled with the timeless beauty of the Jaguar E-Type.