MCLAREN BUILT ITS reputation on high-tech, high-spec, top priced racing cars. Borrowing engineering acumen from its (historically great, currently weak) Formula One team, the British company has produced some truly wondrous road cars, starting with the three-seater F1 in the nineties—the world's fastest production car for a decade—up to the all-new, million-dollar Senna, with a 789-horsepower engine in a vehicle that weighs just 2,461 pounds.

But McLaren has larger aspirations. It's only been seriously building road cars since 2010, but it wants to expand, to reach more buyers with more affordable, practical vehicles. Of course, with supercars, everything is relative. McLaren's "daily drivers" come from its Sports series, made up of cars that start a little shy of $200,000 and offer not much in the way of cargo space.

The company has just expanded that range with the addition of the 570S Spider, a convertible version of the 570S coupe which has been around for a couple of years now, alongside the track-oriented 570GT.

Typically, purists eschew a convertible version of a sports car. Cutting off a roof comes with too many compromises. Without that structural support, the whole frame of the car is weakened, which can impact handling, and make everything shaky and wobbly. So designers have to add strengthening to the sills or under the body, which adds weight, which impacts performance. If you want fresh air so badly, take the yacht out.

McLaren claims you can have your cake, and eat it too—if you can eat cake while the wind blasts you at triple-digit speeds. The 570S Spider, the company declares, is “a convertible without compromise.”

“The carbon fiber tub was engineered to have the strength in it, from the beginning,” says McLaren’s spokesperson, Wayne Bruce. To make the Sports series more usable, McLaren’s engineers cut down the high door sills, which make some of the sportier variants difficult and awkward to climb in and out of, particularly in tight pants or a skirt.

To compensate for that change, McLaren's engineers added strengthening under the car. As a result, the solid roof was never a crucial part of the vehicle’s strength—and cutting it off didn't require any extra support. The addition of a retractable hardtop, with the electric motors to open in in just 15 seconds, adds a forgivable 101 pounds to the vehicle’s weight. And you can operate it at speeds of up to 25 mph, which means you don’t get embarrassed when you try to close it at a red light, but don’t quite make it in time, leaving you sitting there instead of zooming off.

At first glance with the roof closed, it’s hard to tell convertible apart from the coupe version of the 570S. The silhouette is very similar, but the cool, giant, hinged, rear window of the coupe is gone, along with the flying buttresses, that add drama but also downforce at between the roof and the rear of the car. In its place is an openable, flat rear window, that doubles as a wind deflector, to protect your hair do. The rear spoiler is half an inch longer than the coupe’s, apparently to compensate for the slight change in body shape.

The 3.8-liter, twin turbocharged V8 engine is still clearly visible behind the driver. Mated with a seven speed gearbox, it makes the 0-60 sprint in 3.1 seconds feel effortless. The various driving modes firm up suspension or quicken gear shifts, in Normal, Sport, or Track.

There are no buttons on the steering wheel on this McLaren, unlike almost every other modern car. Too bad the 10-inch touchscreen that controls the music and heating was almost impossible to see with the glare from the sun when the roof is down. You'll have to listen to the engine noise and enjoy the breeze. Tough life.

To test that whole practicality idea, I cut short my time in the canyons to take the droptop to the supermarket in Malibu. With the front of the car raised (a clever feature activated with two clicks on a stalk behind the steering wheel, sure to spare many an expensive chin-splitter) I was able to get over the speed humps, and I could open the spectacular dihedral driver’s door, even in a tight spot. It lifts almost vertically rather than swings out, so it’s actually pretty handy. Practical indeed. And you might even have some money left over for groceries.

At $208,000—and that's the starting price—this is not a car for everyone. But you can't deny the engineers who cut the roof off made the 570S Spider a very good all-rounder for a few rich people.