The 675LT Spider is 220 pounds lighter than the roofless 650S and the two share all but 33-percent of their parts. It only gains 88 pounds over the hard top. Dry weight comes in at 2,800 pounds; add another hundred or two for fluids and fuel. Power to weight is an impressive 4.2 pounds per horse.

Only 30 percent of those 220 pounds was taken from the chassis. McLaren found 77 more pounds to axe in the body, 44 from the interior and 22 from the powertrain. It took more than 10 pounds from the electrical system!

The 675LT Spider is 27 percent stiffer in front and 63 percent stiffer in back than the 650S. It’s wider and lower too, and has a faster steering rack — something we instantly noticed in the quiet Scottish backcountry where we tested a Solis yellow edition of the new Longtail Spider.

Few cars look this good with the top down.

It doesn’t stay quiet. Firing up the 3.8-liter V8 brings on a clatter of metallic engine parts and a low thrum from the open rear window behind the seats, and it only gets louder from there. The 675LT Spider somehow both roars and drones on the road. Wind noise seems maximized by the creases in the folding hard top, making it hard to speak to your passenger whether on the throttle or not. The tone of the exhaust note seems fixed, only getting louder or quieter as we blip through the gears. At low rpm it hums loudly, at about 2,500 it gets a bit softer — get your conversations in now — and then bellows after that. But this car isn’t a GT, it’s not made for European road trips or Pacific Northwest jaunts. Get a Jaguar if you want something that’ll eat up highway miles. The lighter, stiffer, faster 675LT Spider is made for mountain grades, the back roads and the racetracks.

It’s a little slippery in the mid- to northern Scottish countryside; even when it’s sunny, the ground stays moist from the gray rain clouds passing through. We do get to go flat-out in spots and when we do, we can tell where your hypothetical $372,600 goes.

In every gear, at any rpm, when we push the weighted gas pedal, the 675LT gets up and runs like a greyhound on fire. Grab a downshift for dramatic flair and right when you pass a few old folks on vacation, grab an upshift. A single shotgun blast erupts from the rear end, sending invisible shock waves across the brown-but-greening hills, confusing sheep and sending smaller animals underground.

The only place to find a badge on the McLaren 675LT Spider.

When McLaren told us that both paddles will do upshifts and downshifts, we were livid. Thankfully, before we spouted off about why that’s wrong and bad, the company noted that both paddles are made from one piece of carbon fiber on a rocker switch. Pull back on the left for downshift, back on the right for upshift. All is right with the world. But, if you need it, you can flick the left one forward for an upshift, and the right one forward for downshift. That’s just adding value, we suppose.

The 675LT has normal, sport and track driving modes for both the powertrain and the handling — both can be adjusted independently. The handling switch controls the dampers and steering weight while the powertrain adjusts the engine and transmission. In normal mode, the seven-speed gearbox cuts fuel for a split second between shifts, McLaren calls it cylinder cut. In sport mode it uses ignition cut, adopted from Formula One, which sees a momentary cut of the spark on shifts. That’s when you get the big whip crack sound and finally “inertia push” which “harnesses the built up kinetic energy to deliver an impulse of torque as the next gear is engaged, ensuring no drop in performance as the driver moves up through the gears.” All of them are in the millisecond range, so you can’t really go wrong.

McLaren’s ProActive Chassis Control suspension with active damping keeps everything marble-countertop flat in the bends, while lift and dive are basically nil. The dampers are connected to a gas reservoir which can amp up the stiffness when necessary and tone it down when going fast in a straight line. The double wishbones and uprights are derived from the even more extreme P1 hypercar, giving the Spider a high-strung driving feel. The 675LT handled bigger potholes surprisingly well, even in sport mode, and never really made us wince in the cabin. McLaren did away with the now-unnecessary mechanical antiroll bars, which both reduces weight and increases wheel articulation.

Pirelli P Zero Trofeo R tires are standard, 19-inch in front, 20-inch in back, as are wagon-wheel-sized, unfadeable carbon ceramic brakes with a stiff pedal that takes a little muscle to plant down. The 675LT also gets the company’s “brake steer” system, which can grab the inside rear brake in a turn, helping point the nose towards the apex.

Now, forget about all of that because this car’s killer app is the airbrake. At some point, when driving this car, you’ll be in triple digits speeds feeling confident in your coordination. Something will happen, a bird, a cop, a kitten, and you’ll go to the brakes hard. That’s when the snowboard spoiler goes vertical, catching all of the nearby air and dropping speeds to something a little more manageable. It gets light in the nose, just for a second, but the spoiler drops well before speeds that you’d need to get around a corner. It’s big enough to block the entire rearview mirror and we hit it hard a handful of few times just to see it work.

The suede-covered steering wheel is soft in the hand and has a nice amount of heft to it. The hydraulic system is electrically boosted, but if we had to guess by feel, we couldn’t have told you that. It feels very analog. Putting an even finer point on it, we just drove a few other supercars, including a few of this one’s competitors and found the steering feel lacking compared to the 675LT. We’d say something like the all-wheel-drive Audi R8 is good for beginners, but you want some experience before piloting this British beast.

The cabin is mostly dark and covered in suede and matte carbon fiber. The central screen, about the size of an iPhone 6 Plus vertically, seems a little small compared to most cars today and it’s a little wonky to use. One central button brings you back to the home screen, but it takes few presses to get back to the music area and skip a song if you’re looking at navigation. We’re riding in the no-cost, suede-covered race seats for this test, which don’t have an adjustment for height. If you’re a shorter driver you’ll have to choose the heavier electric jobs to get up over the tall central tach. There are a few different versions of the race seats, but at 5-foot-10 and 160 pounds, these were perfect for us. They’re supportive in the lower back, and have stiff bolsters to hold you in place at the hips and at the shoulders. We didn’t get any backside numbness over six or so hours, but be warned; there is really no way to get in this thing gracefully. Blame the vertical doors. We had to go in butt first, and swing our legs over the bolster — some McLaren execs have obviously been practicing — swinging in without getting hung up.

Lastly, we love the one giant windshield wiper, but spraying off the dirt while driving sent all of the blue fluid into the cabin through the open windows and down the suede doors. Seems like bad engineering, or maybe the wind was just too strong. A better solution? Get out of the rain and road spray in Scotland — this is a convertible, dammit.

It takes about 30 seconds to put the top up.

The 675LT Spider starts at $372,600 and doesn’t go up too much from there, unless you start customizing from the McLaren Special Operations team. That’s still a bit more than the latest Ferrari 488 GTB Spider, but it’s also a full step more aggressive than the GTB. It’s also nearly 600 pounds lighter than the GTB, so it feels a good bit faster. But does it say the same thing (to onlookers) as a Ferrari does? Probably not.

Maybe that’s what McLaren is talking about when it says it has a marketing problem. This car is every bit as super as the ones we go to first in our minds, but for some reason it doesn’t have the cachet outside the hyper-enthusiast community. A little more F1 in the U.S. might help that, as would introducing a few new cars before they sell out.

On the other hand, selling every car you make? That’s better than the alternative, and what we call a good problem, here in the business.