The fanatics at McLaren can’t sit still for long. You could almost hear their feverish collective brain working with an open-top 720S when they presented the coupe at Geneva 2017. The idea made sense—the coupe is fairly stiff already, and wouldn’t need much additional weight to make a topless version structurally feasible.

And the 720S Spider was born. And it makes one wonder why anyone would buy the coupe when the open-top option is available—even if the coupe wasn’t sold out through the not-so-near future.

Looking something like a perfect summer day, the variation on the upper-tier McLaren model is less than 110 pounds heavier than the coupe 720S. The key to the modest weight gain is the coupe carbon-fiber tub, which the company calls the ‘Monocage II’; the design improves on the original Monocage of the 650S (the Senna gets the Monocage III, in case you were wondering about Monocage evolution).

What that indicates, of course, is that the open-top 720S Spider and the 720S coupe should be very close to one another when it comes to launch times. As a matter of fact, they’re identical out of the gate; both spring to 60 in 2.9 seconds.

The optional retractable electrochromic glass top is acute performance auto designing of the highest order, and it represents another reason to go with the Spider. It’ll gradient-tint at the press of a button, and neatly slides away when open-top driving is desired. Very cool.

New wheels, new colors (electric-like ‘Belize’ blue and El Dorado-inspired ‘Aztec’ gold), and a price of $315K. Deliveries begin in the spring.