All That Glitters: 2020 McLaren 720S Spider vs. 2020 Mercedes-AMG GT R Roadster vs. 2021 Porsche 911 Turbo S Cabriolet

The numbers are dazzling, if not staggering:
$825,110 worth of open-air supercars.
1,927 horsepower.
1,674 lb-ft of torque.
The shapes of these machines, especially in these colors, make children jump and squeal with joy—while most adults wish they weren’t quite so self-conscious so that they could do the same.
Because you’re wondering, oh yes, some grownups act like kids around these things (yours truly first and foremost). This trio truly is a collection of rare, exotic beasts. Each one represents a topless version of its respective companies’ near-pinnacle performance car. I say “near” because McLaren just unveiled the 765LT, Mercedes-AMG makes the GT R Pro, and Porsche, well, you just know there will soon be a GT2 RS that makes this car seem like a snail. Plus, all three manufacturers are in the hypercar business, to varying degrees (P1, Senna, Project One, Carrera GT).

The question, then, is, “Why?” Why would an automaker take a perfectly good supercar and hamstring it by removing rigidity and adding weight? That’s the question you’d ask before you’d spent a few days driving this shimmering trio around some of Southern California’s greatest roads. After doing so, the only question is, “Why the hell not?”
I’m going to asterisk this comparison test at this point. First of all, we still can’t test cars, so I don’t have any objective numbers to point you to. Sorry. Also, yes, we should have had the McLaren 600LT Spider instead of the 720S Spider, as the former’s base price of $259,000 is much more in line with the other two than the latter’s starting price of (yikes) $317,500. Don’t even think about the as-tested price of (gulp) $372,750. However, there wasn’t a 600LT Spider available. So we took one for the team and grabbed the only convertible Macca had on offer, the 720S Spider. The sacrifices we all make, right?
I’d also like to toss out a caveat for the AMG GT R Roadster. It’s old. Say huh? True, the GT R Roadster is only about a year old. I’m talking about the platform itself, going back to 2014. However, that’s only the current generation. The C190/R190 (C190 is Mercedes geek-speak for the GT Coupe, R190 means GT Roadster) is actually a modified version of the C197/R197 Gullwing, aka the SLS AMG. That chassis goes back to 2009, and the GT body-in-white is essentially the same structure but with 50mm lopped out of the wheelbase.
I’m mentioning these caveats because the Porsche 992 Turbo S is brand-spanking-new. We know that AMG will be introducing an all-new GT in the not so distant future. Please don’t read this as me making excuses for the AMG, but more like when the SLS AMG was developed, 19-inch R-compound tires were cutting edge. The Porsche showed up on 21s. The persistence of time and all that.

Intriguingly, these three roadsters do not follow a set template. The AMG is front-engine, the McLaren has a mid-mounted engine, and the 911’s mill lives behind the rear wheels.
The GT R Roadster uses a racy, modified version of AMG’s 4.0-liter twin-turbo V-8, called M178. You can think of it as a dry-sump version of the more ubiquitous M177, which is used in every other AMG with a V-8, including, confusingly, the GT 63. Its 577 hp and 516 lb-ft of torque flow down a carbon-fiber driveshaft to a seven-speed dual-clutch transaxle.
The 720S also uses a dry-sumped 4.0-liter twin-turbo V-8 that makes 710 hp and 568 lb-ft of torque, though there’s one major difference—the McLaren uses a flat-plane crankshaft. Flat-plane V-8s rev quicker, are typically lighter, and make turbocharging (a bit) easier. However, they vibrate much more (there’s no inherent secondary balance like a cross-plane V-8) and tend to be more brittle. Great for race cars, problematic elsewhere. Like the AMG, the McLaren employs a seven-speed dual-clutch transaxle.
The Turbo S is different still, with its rear-mounted 3.8-liter twin-turbo flat-six producing 640 hp and 590 lb-ft of torque. Like the other two, the Porsche has a dual-clutch transaxle for a transmission (a transaxle is just a combination of a transmission and a differential where driven axles exit the case, as opposed to forces being sent down a driveshaft to a differential), with eight forward gears instead of seven like the other two entrants. The Porsche drives all four wheels, whereas the others are both RWD. The AMG and the Porsche have all-wheel steering, and all the cars have carbon-ceramic brake rotors, but only the Porsche has four seats, even if two of them don’t actually work.

As for performance, all are lunatic-quick. Let’s look at comparables, as you real estate types love to say. The McLaren 720S coupe hits 60 mph in 2.5 seconds and runs out the back of the quarter mile in a startling 10.1 seconds at a blazing 141.5 mph. That last one is 0.1 second off the 887-hp Porsche 918 Spyder. Again, the 720S is rear-wheel drive.
The 991.2—meaning the previous-generation 911 that this one replaces—Porsche 911 Turbo S coupe also hit 60 mph in 2.5 seconds before flying through the quarter mile in 10.5 seconds with a trap speed of 131.8 mph. (We never tested a 991.1 or 991.2 Turbo S Cabriolet.) The nearly 10-mph difference in trap speeds means the McLaren is making a lot more juice than that old 580-hp Porsche. As Top Gear America co-host Jethro Bovingdon says, “All McLarens make 800 horsepower.” The McLaren we tested also weighed 390 pounds less than the porker Porsche, 3,167 vs. 3,557 pounds.
As for the AMG GT R, the coupe version weighs 3,680 pounds, hits 60 mph in 3.4 seconds, and runs the quarter in 11.3 seconds at 129.0 mph.
The McLaren and Porsche are two of the quickest cars we’ve ever tested, but the 992 Turbo S will be quicker than the old one, and the Spider version of the 720S will be (a touch) slower.
Also, if the AMG GT R were up against nearly any other competitors, its numbers would appear stellar. Convertibles are usually heavier than their hardtop counterparts. By removing stiffness, you typically need to brace the chassis. Even with a super-stiff carbon-fiber tub car like McLaren’s, the folding roof bits add additional weight.

The Fashion Show
“I love, love, love the looks of it,” Miguel Cortina said in regard to the 720S Spider. He certainly has a point. It’s been more than three years since we first laid eyes on the 720S, and the looks have only improved. It’s the best-looking mid-engine design since the Lamborghini Huracán showed up in 2014. Head of McLaren design Robert Melville and his team pulled off the nearly impossible: The Spider might look even better with the top down. That never happens.
The GT R certainly loses something in roadster form, though I will say there are certain roofless angles that look fabulous. Especially in this outrageous ($9,900) metal-flaked yellow. Best rear end in the business? The answer remains yes. The 911 Turbo S definitely looks worse as a convertible and worse still with the roof stowed, especially in this odd, dull orange. There’s just a pudginess to it that’s absent from the hardtop. Solution? Hey, Porsche, Targa Turbo! Do it.
Inside the cars, the tide turns. “I know I’m going to get hate mail,” Cortina said, “but the McLaren’s interior could be better.” I like the inside of the 720S just fine, but I know what he means. There’s a homebrewed feel to the Brit that’s simply absent from the Germans’ cabins. True, there’s a spaceship vibe happening—a spaceship made out of wetsuits.

The Porsche, meanwhile, is all business. Well, all that red leather makes it a high-end brothel, but that’s still a business. The controls are minimal and intuitive, and for the first time in Porsche history, the cupholder works about two-thirds of the time.
That said, the AMG steals the interior show. As Miguel said, “The interior is really polished—elegant design, fancy air vents, and a lot of cubbies to hold your belongings.” However, the AMG had the worst seats—narrow, with thin padding. This is a trait common to front-engine cars that have transmissions (or in this case, torque tubes) bisecting the cabin. Side-to-side space is at a premium, and the seats pay the price by shrinking. Think of the last couple generations of Corvette or Dodge Viper, RIP. The Porsche had the best seats of the test.
Behind the Wheel
Roof or no roof, all three of these machines are supercars. However, because we’re unable to test or lap cars, we don’t have empirical numbers to guide our anecdotal hands, guts, and brains. As such, ranking these three comes down to good, old-fashioned feelings—which, when you’re deciding between cars of this ilk, is what it really comes down to anyway.
“I got goosebumps as I was driving up the mountain,” Cortina said of the 720S Spider. “This thing is fast—very fast.” Do we call Miguel Captain Obvious? Sometimes.

Senior editor Scott Evans added: “We used to call the 911 Turbo S ‘weaponized speed,’ but McLaren has usurped that title. There’s so much motor in this thing. Everything else is clouded out of your brain.”
As for my own notes: “Have I ever driven up Angeles Crest quicker? Doubtful. It does 100 mph in third gear. I should clarify that it calmly does the hundo in third.” It’s such a bizarre/unique experience, the ability to go that quick with that much control.
You find yourself serenely thinking, “The glass panel above my head starts vibrating at 100 mph, stops at 106 mph, but then resumes shaking with slightly more gusto at 108 mph. I’ll have to investigate. But after lunch.” This car is just not normal. There are no straights with this car; you’re constantly arriving at corners. As I’ve long said, alien technology for the street.
Although perhaps not a spaceship from another world, the AMG Roadster is no slouch. Every time I looked, I was bordering 90 mph. In this company, the car might seem a bit outgunned on paper, but seat of the pants, the power felt competitive. Keeping up with the other two was neither a problem nor an issue. This impression was bolstered by the fact that the GT R Roadster is by far best-sounding of the trio.

The Porsche’s sport exhaust manages to change the sound from two industrial-strength hair dryers to four, but as Evans pointed out, “Even with the exhaust closed, it’s got more of that classic angry sewing machine chatter than it’s had in years.” Sure, but the AMG crushes it, sonically speaking. Puts a hurt on the McLaren, too.
Even with a flat-plane crank, the McLaren’s twin turbos muffle the engine. I’ve been saying this for years, but only AMG seems to be able to make turbocharged motors sound mean and spiteful. With the roof lowered, the engine’s roar and the exhaust’s crackle are that much better. Why are you buying a convertible over a coupe in the first place? I’d argue for the visceral experience. The AMG is quite dramatic. That said, the 7,000-rpm redline is too low. Please raise it to at least 8,000 rpm, thank you.
As for the 992 Turbo S, this is something new. Something totally different. “This is not the 911 Turbo I remember,” Evans said. “That was a Grand Touring car but not a Porsche GT in the Weissach sense of the term. This Turbo S is a Porsche GT car. It’s just missing the number.”
Hard to argue, especially when said Turbo S is equipped with the PASM Sport suspension that was developed by Porsche’s racing division in Weissach. “More than anything, the Turbo S is a beast to drive,” Cortina said. Beast is a good word, as the Turbo S’ forward thrust is animalistic. Its 640 horsepower will grab all the headlines, but it’s that torque figure—590 lb-ft of the good stuff—combined with the traction of all-wheel drive that makes this Porsche such a monster.

The McLaren is shockingly quick in a straight line, but the Porsche is gobsmackingly quick everywhere—especially blasting, clawing, scraping its way out of corners. Ready for it? I think going A to B on a twisting road, the 911 is quicker than the 720S.
One perennial knock on the AMG GT R coupe is that the rear suspension is comically stiff. Like the Chevy Camaro ZL1 1LE, the dampers are of the spool-valve variety and supplied by Multimatic. Long story short, spool-valve dampers work wonders on buttery-smooth racing tarmacs then beat your lower back with a 10-pound hammer on real, actual roads. Both the GT R Coupe and big dog Camaro ride atrociously.
My big worry going into this comparison was exactly that. I’m not sure if it’s the added weight over the rear of the GT R Roadster or if AMG actually retuned the dampers, but the soft-top’s ride is much, much better. Put it like this: Whenever I’m asked about the GT R coupe, I immediately dismiss it and say instead, check out the GT C coupe. You lose 27 horsepower but gain everything else. Here? I’d recommend the GT R Roadster over the GT C version.
However, the GT R’s handling was the least confidence-inspiring of the three. “The steering is too quick,” Cortina said. “You sort of have to trust the car and turn just as you’re entering the corner. The hood feels humongous.” Evans added that it “feels like you’re sitting on the rear axle and the front of the car turns before you do.”

Does this mean the GT R handles poorly? No, it’s just an odd sensation. Once you learn to trust it, I’d argue it handles about as well as the other two. It’s just not the most satisfying way to drive. I appreciate how efficient the GT R’s steering is—I don’t think my hands went past 45 degrees—but it’s too juiced. Evans again: “The Porsche required a flex of the arms to steer. This requires a twitch.”
I suspect much of this is due to AMG’s aggressive rear-steering setup. Years ago, on a prototype drive of the GT C I asked then-AMG boss Tobias Moers (in May, he was named the new CEO of Aston Martin) the difference between his all-wheel-steering system and Porsche’s. Basically, Porsche uses one electric motor for both wheels, and AMG uses two. AMG therefore is able to steer the rear wheels a degree or so farther. This strategy works in terms of getting the GT R around corners—but it just feels off.
The McLaren also has some feel issues. “This is the only one of the three that gave me sweaty palms,” Evans said. “The steering is both a blessing and a curse. At speed, it almost feels like a manual rack, it has so much kickback. It’s wonderful, but like an old manual rack, things get interesting when you brake. The 720S tramlines and moves around. The front tires never quite feel like they’ve got enough contact patch for the amount of stopping power the brakes are making. You have to be on top of the steering at all times.”

I concur; the steering is beautiful. That said, the 720S is one of the last cars on sale that fills me with terror. A Koenigsegg is another. The steering is perfectly weighted and requires low inputs. Grip is good, though the car mostly grips via the rear tires. The fronts are a touch busier. Those front tires have been and remain a relatively skinny 245 width. I’m still waiting for McLaren to do the right thing and give this car some proper tires. The new 765LT will come on race-compound rubber, but McLaren should at least make the P Zero Trofeo R tires an option on the 720S.
Like the McLaren, the Porsche is also on standard Pirelli P Zeros (the AMG is on R-compound Michelin Sport Cup 2s), but there was not a single complaint about the way the 911 handled. Miguel was nearly speechless, stammering, “The 911 truly delivers on every front.”
Scott was a bit more talkative: “You don’t have to manhandle it. Just be firm. Driving this car reminds me of target practice. Every motion is a squeeze. Control your breathing then squeeze the throttle. Squeeze the brakes. Squeeze the muscles in your forearms. Hit the target.”

I climbed into the Porsche thinking—strongly thinking—that there’s no way on earth either German had a chance against the maniac Brit. They’d both be outclassed. However, during my run up the mountain in the Turbo S, I realized that it’s just as quick as the 720S and inspires about three times the confidence.
That’s the key: confidence. Within a half mile I knew everything about the car and just started flinging it. The McLaren takes a few miles for you to build yourself up to take advantage its true potential. I’m not sure if I ever would get to the point of trusting the AMG the way I do the Turbo S, mostly due to the GT R’s steering.
Is this another win for another Porsche? Yeah, sorry. It’s true. If you recall the 1997 film The Devil’s Advocate, Al Pacino’s Satan is lecturing Keanu Reeves about what’s wrong with the latter’s “Florida stud” persona: “Look at me—underestimated from day one. You’d never think I was a master of the universe, now, would you?”
That’s this Porsche. Staring at the three, the Turbo S is a wallflower, especially in that (awful) shade of orange. The 720S is one history’s wildest-looking supercars (I find it bloody sexy), and the AMG is equal parts muscular and stunning. Not knowing anything, I think the Porsche would be the last kid picked for kickball. But as Pacino says of his devilish character, “They don’t see me coming.” We sure didn’t with this Turbo S.

First Place: 2021 Porsche 911 Turbo S Cabriolet
An upset win if there ever was one. Porsche is more unrelenting than ever before. The new Turbo S picks up where the GT2 RS left off.
Second Place: 2020 McLaren 720S Spider
A cruise missile with four wheels. Pure exotica. 720S Spider customers will no doubt crave a 911 Turbo S for daily-driving duties.
Third Place: 2020 Mercedes-AMG GT R Roadster
Down on power but high on charm, this AMG most likely beats all convertibles on earth save for the above two rivals.

2021 Porsche 911 Turbo S Cabriolet
2020 McLaren 720S Spider
2020 Mercedes-AMG GT R Roadster

DRIVETRAIN LAYOUT
Rear-engine, AWD
Mid-engine, RWD
Front-engine, RWD

ENGINE TYPE
Twin-turbo flat-6, alum block/heads
Twin-turbo 90-deg V-8, alum block/heads
Twin-turbo 90-deg V-8, alum block/heads

VALVETRAIN
DOHC, 4 valves/cyl
DOHC, 4 valves/cyl
DOHC, 4 valves/cyl

DISPLACEMENT
228.6 cu in/3,745 cc
243.7 cu in/3,994 cc
243.0 cu in/3,982 cc

COMPRESSION RATIO
8.7:1
8.7:1
9.5:1

POWER (SAE NET)
640 hp @ 6,750 rpm
710 hp @ 7,500 rpm
577 hp @ 6,250 rpm

TORQUE (SAE NET)
590 lb-ft @ 2,500 rpm
568 lb-ft @ 5,500 rpm
516 lb-ft @ 2,100 rpm

REDLINE
7,200 rpm
7,500 rpm
7,000 rpm

WEIGHT TO POWER
5.9 lb/hp
4.6 lb/hp
6.5 lb/hp

0-60 MPH
2.4 sec (MT est)
2.6 sec (MT est)
3.5 sec (MT est)

TRANSMISSION
8-speed twin-clutch auto
7-speed twin-clutch auto
7-speed twin-clutch auto

AXLE/FINAL-DRIVE RATIO
3.33:1/2.03:1 (front), 3.02:1/1.84:1 (rear)
3.31:1/2.27:1
3.88:1/2.68:1

SUSPENSION, FRONT; REAR
Struts, coil springs, adj shocks, anti-roll bar; struts, coil springs, adj shocks, anti-roll bar
Control arms, coil springs, adj interconnected shocks, hydraulic anti-roll and downforce resist; control arms, coil springs, adj interconnected shocks, hydraulic anti-roll and downforce resist
Control arms, coil springs, adj shocks, anti-roll bar; control arms, coil springs, adj shocks, anti-roll bar

STEERING RATIO
12.5-14.1:1
15.2:1
12.7:1

TURNS LOCK-TO-LOCK
2.5
2.5
1.9

BRAKES, F;R
16.5-in vented, drilled, carbon-ceramic disc; 15.4-in vented, drilled, carbon-ceramic disc, ABS
15.4-in vented, drilled, carbon-ceramic disc, 15.0-in vented, drilled, carbon-ceramic disc, ABS
15.4-in vented, drilled, carbon-ceramic disc; 14.2-in vented, drilled, carbon-ceramic disc, ABS

WHEELS, F;R
9.5 x 20-in; 12.0 x 21-in forged aluminum
9.0 x 19-in; 11.0 x 20-in, forged aluminum
10.0 x 19-in; 12.0 x 20-in, forged aluminum

TIRES
255/35R20 97Y; 315/30R21 105Y, Pirelli P Zero NA1
245/35R19 93Y; 305/30R20 103Y Pirelli P Zero Corsa MC
275/35R19 100Y; 325/30R20 106Y Michelin Pilot Super Sport Cup 2 MO

DIMENSIONS

WHEELBASE
96.5 in
105.1 in
103.5 in

TRACK, F/R
62.4/63.0 in
65.9/64.2 in
66.7/66.2 in

LENGTH x WIDTH x HEIGHT
178.6 x 74.9 x 50.8 in
178.9 x 76.0 x 47.1 in
179.7 x 78.6 x 49.4 in

TURNING CIRCLE
35.8 ft
39.7 ft
37.6 ft

CURB WEIGHT
3,800 lb (MT est)
3,250 lb (MT est)
3,750 lb (MT est)

WEIGHT DIST., F/R
40/60% (MT est)
42/58% (MT est)
47/53% (MT est)

SEATING CAPACITY
2 + 2
2
2

HEADROOM
37.9/32.5 in
37.5 in
38.0 in

LEGROOM
42.2/27.2 in
42.4 in
43.5 in

SHOULDER ROOM
52.6/47.9 in
51.2 in
58.4 in

CARGO VOLUME
Front: 4.5 cu ft/rear seats folded: 9.3 cu ft
Front: 5.3 cu-ft/rear: 2.0 cu-ft
5.8 cu ft

CONSUMER INFO

BASE PRICE
$217,650
$317,500
$191,745

PRICE AS TESTED
$236,120
$372,750
$216,240

STABILITY/TRACTION CONTROL
Yes/yes
Yes/yes
Yes/yes

AIRBAGS
6: Dual front, side/head, knee
6: Dual front, side/head, knee
8: Dual front, side, head, knee

BASIC WARRANTY
4 yrs/50,000 miles
3 yrs/Unlimited miles
4 yrs/50,000 miles

POWERTRAIN WARRANTY
4 yrs/50,000 miles
3 yrs/Unlimited miles
4 yrs/50,000 miles

ROADSIDE ASSISTANCE
4 yrs/50,000 miles
3 yrs/Unlimited miles
4 yrs/50,000 miles

FUEL CAPACITY
17.6 gal
19.0 gal
19.8 gal

EPA CITY/HWY/COMB ECON
20/25/22 mpg (MT est)
15/22/18 mpg
15/20/17 mpg

ENERGY CONS., CITY/HWY
169/135 kW-hrs/100 miles (est)
225/153 kW-hrs/100 miles
225/169 kW-hrs/100 miles

CO2 EMISSIONS, COMB
0.88 lb/mile (est)
1.11 lb/mile
1.15 lb/mile

RECOMMENDED FUEL
Unleaded premium
Unleaded premium
Unleaded premium

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