Underneath is the "Touring Deck" — a spot for luggage that McLaren basically created out of thin air. The hinged glass door gives easy access to the compartment. And, as McLaren is a British company (where they drive on the wrong side of the road, remember), the door is customized depending on if the car is right- or left-hand drive, and always opens toward the curb. Very thoughtful.

It's only once you walk around the side that you see the GT's party piece: an enormous glass door that sits atop the engine compartment and changes the entire look of the car.

The McLaren 570S and 570GT share the same chassis, engine, suspension, and steering setups (McLaren says the latter two have been slightly tweaked to make the car a touch more comfortable, though you'd be hard pressed to tell the difference), and most of the exterior is identical, particularly when looking from the front.

I drove both over two days in England in late June, the 570GT on the road and the 570S on the track at the famed Brands Hatch circuit. Though the cars are unsurprisingly similar in feel, they nonetheless have very different outlooks on the world.

The other big difference between the 570S and the 570GT is best experienced from inside the latter. Sit in either the passenger or the driver's seat and simply look up. Above your head is a massive glass roof that gives the car a wonderful sense of openness and is perfect for long blasts through gorgeous countryside.

That fixed glass roof might be fine in England, where only two of my seven days were sunny. But in Phoenix or Abu Dhabi, the sun would become uncomfortably warm — and there's no sunshade. That's why McLaren is working on an electrochromic smart glass that can tint itself, adjusting how much sunlight gets through. Boeing uses the tech in the windows fitted to its 787 Dreamliner, and McLaren says it should be announced in the next few weeks.

the 570gt goes from 0-60mph in 3.3 seconds

Thanks to a 123-pound weight gain, the 570GT is slightly slower from 0–60mph than its track-focused brethren, 3.1 vs. 3.3 seconds. Braking from 60 to 0 mph is identical and faster still, achieved in just 102 feet and 2.9 seconds according to the McLaren stat sheet.

Aside from picking whichever one has a shorter waiting list, choosing between the 570S and the 570GT seems to be rather personality-driven. To the uninitiated, both cars appear quite similar. But look at them for a little longer and you start to notice a very different design philosophy.

McLaren says that if you're the type of person who wants a more aggressive, sporty car, you'll be naturally drawn to the look of the 570S, with its sharper angles and darker rear deck.

If you like smooth lines and a flowing form, you'll lean more toward the 570GT and the different sort of driving style that it allows. You're not heading to the track every weekend (though you certainly could), but instead to Napa or your cabin in the Catskills, complete with what, for a supercar at least, is a rather insane amount of luggage.

And so we come back to our questions from the beginning. What's the difference? And how do we choose?