2017 Bentley Continental GT V8 S Convertible vs. 2017 Mercedes-AMG S63 Cabriolet

From the December 2016 issue

Dad bought a new Cadillac Eldorado convertible in 1976. GM touted it as the last of the big droptops, a majestic parting shot seemingly designed to transport prom queens, grand marshals, and Boss Hogg types into an increasingly ­dystopian, gas-rationed future. Dressed in triple red with every option, including fuel injection, automatic high-beams, power everything, and a hard tonneau “parade boot,” that 18.7-foot luxo-barge weighed 5231 pounds and was motivated via an 8.2-liter V-8 under a hood so long you could land an Airbus A380 on it. No one can say that Cadillac let the convertible go g­ently into that good night.

What no one could have imagined back in 1976 was that big ­convertibles would exist at all 40 years later, much less as 500-plus-hp chariots for the same well-to-do neighborhoods that Cadillac once owned. In a world of $2.50 gas and ever-growing stock portfolios, the parade car has returned. Using a big, thirsty, open-air sled to declare “I’m rich and deserve this” is again possible without having to resort to the classic-car market.

After a four-decade hiatus, Mercedes is back to building full-size convertibles. Save your letters; we’re not counting the E-class–based 1993–95 cabriolet because it did not achieve true pulchritude. In no dimension, except maybe build quality, does it measure up to this S-class–derived four-seater. Available in three flavors, Merc’s convertible is a leather-packed bullet aimed squarely at the Bentley Continental GT convertible. Constant updates have kept the now 12-year-old Continental as relevant as any car costing more than $200 large can credibly be.

Admittedly, when conducting a comparison of cars this ludicrously expensive, logic is trumped by baser stuff. Cadillac certainly wasn’t thinking logically when it built its 8.2-liter V-8. Just as with old stars that grow so large they collapse upon themselves, Cadillac’s 500-cubic-inch supergiant, in its final year, made just 190 horsepower (215 with fuel injection) and 360 pound-feet of torque, numbers that Mercedes can now match with a 2.1-liter turbo-­diesel. But with two turbochargers and more than 500 horsepower each, these modern V-8s certainly recall that Cadillac’s excess.

Bentley and Mercedes do offer larger 12-cylinder engines, but we chose the V-8 versions because upping the cylinder count adds weight, complexity, and cost without, in our opinion, improving the driving experience. Okay, so sometimes logic does trump ­emotion, even in the illogical world of the big convertible.

On the Mercedes side, we selected the 577-hp AMG S63 that starts at $178,325, here to do battle with the 520-hp Continental GT V-8 S convertible that opens at $234,525. AMG’s 5.5-liter blown V-8 is the perfect foil to Bentley’s 4.0-liter blown V-8. Because it’s not exactly Bentley’s engine—it’s the same unit found in a number of Audis—this is sort of a proxy war between two German rivals.

Cloth-top, two-door personal luxury machines might perplex those of us without vacation homes and yachts, but as with the Eldorado of the ’70s, there’s a seductive magic to a comfortable, tech-filled premium convertible with a V-8 heart.

It’s easy to forget that the S63 ragtop offers 577 horsepower and the ability to leap to 60 mph in 3.7 seconds. It ably performs feats of strength, but this big AMG, from its quiet performance to the caressing fingers of its massaging seats, lulls you into an effortlessly comfortable and nearly perfectly bored state. Maybe that’s why Mercedes included Attention Assist here.

We found our attention fading because the S63 doesn’t seem to want or need our involvement. It’s a hugely complex and sophisticated machine full of electronics and driver aids that are always on alert and ready to take over. Meticulous engineering has taken this car to the precipice of autonomy. It seems to be saying: “I heard what Dr. McIntyre told you about your PSA score. I wouldn’t worry. Just sit back and enjoy a massage. Classic or hot stone?”

Participate in driving and you’ll quickly become annoyed with the seven-speed automatic. In place of a torque converter, this planetary gearbox has a multiplate startup clutch bathed in fluid. The clutch is slow to engage when accelerating from a stop, and the car jerks and bucks in stop-and-go traffic. Unlike other AMGs with this transmission, there’s no launch control, so we have to wonder why they bothered. Not that you really need launch control with this much power.

Steering is light and creamy, but we’d like it to be a bit more tactile. Bend it into a corner and the S63 remains flat and poised all the way up to its 0.89-g limit. When forcefully engaged, there’s a great chassis here and the AMG hustles when pushed, but the agility is buried down in the basement under 4929 pounds of steel, glass, and leather.

Two big flat-panel displays dominate an instrument panel that executive editor Aaron Robinson called the “dashboard by Best Buy.” Benz’s electronic gauges beautifully mimic analog dials, and selecting the AMG display adds oil- and transmission-temperature dials, but the entire panel is set too high and the small-diameter steering wheel partially obscures the dials unless you raise the wheel to an awkward height. If you’re going to substitute instruments for an iPad, at least make it so that the display can be moved or configured in a number of ways. Benz doesn’t, so it might as well have stuck with more-sporting analog gauges.

The S63’s racy getup is inconsistent with its driving character. It’s akin to painting Boss Hogg’s Caddy orange and affixing “01” stickers to its doors.

There’s a lot to love about the rest of the interior. Bengal-red-and-black leather costs an extra $3250 and wraps nearly every bit of the cabin. Carbon-fiber and black-lacquer-wood trim, a $3700 option, fills in the remaining gaps. At 70 mph, only 63 decibels find their way through the thickly padded top, which makes the S63 the perfect place to hear every one of the 1540-watt Burmester audio system’s 24 speakers. It’s possible that this car’s older clientele will only listen to AM radio over this spectacular $6400 system. Not to worry; Rush, either the man or the band, comes through loud and clear.

A faint quiver through the structure is the only hint of its missing roof, or that this car is in some small way technically fallible.

At greater fault is the car’s personality: Its demeanor keeps you at arm’s length, Mercedes having refined this convertible to the point of joylessness. It’s a sad thing to say about a company that once filled this niche in the late ’60s and early ’70s with the W111 280SE—the steel, chrome, and leather equivalent of Grace Kelly.

Back in 2004, a Continental GT finished last in a comparison test against a Ferrari 612, an Aston Martin DB9, and a Mercedes-Benz CL600. Running in that group, the Continental felt like a whale among sharks. Since then, cars have continued to get heavier and more complex while the Continental has enjoyed a steady stream of enhancements that have transformed it from a krill eater to a seal killer.

Of the many changes over this orca’s life cycle, perhaps the most dramatic is the addition of Audi’s 4.0-liter V-8. Without the twin-turbo W-12 anchor weighing down the Continental’s front end, the hardtop and the convertible Contis were transformed into relatively lighter and livelier machines. The convertible’s skidpad grip is a lack­luster 0.81 g, yet the Bentley never wants for grip on the road and has no trouble staying glued to the S63’s rear bumper.

With 55.4 percent of its 5572 pounds on the nose, the Continental is nowhere near as balanced as the AMG. But the steering reacts to the front Pirelli P Zero tires’ torture with clear and natural feedback, the kind cars enjoyed before electric power-steering assist became the norm. As with Bentleys of yore, the Continental glides along with the relentless inertia of a steam train, even at 150 mph.

Audi, er, Bentley offers two versions of its twin-turbo 4.0-liter V-8. In the S version, it makes 520 horsepower and 502 pound-feet of torque; lesser versions subsist on a mere 500 horsepower and 487 pound-feet. Even with the S tune under the hood, Bentley’s GT can’t match the acceleration of the 643-pound-lighter S63. A run to 60 mph takes 4.3 seconds, and the quarter-mile passes in 12.8 seconds at 111 mph. Acceleration lags behind the AMG’s, but the timbre of the Bentley’s V-8 playing through the $2580 “Sports Exhaust” is warmer and more honeyed than the AMG’s metallic rasp.

On the street, the Bentley’s old-school conventional eight-speed automatic switches gears undetected and pulls away from a stop with fluid ease. In any mode other than the hardest setting, the air suspension is graceful and unperturbed by impacts encountered by the 21-inch wheels. Other cars have aped some of the Bentley’s design language, but so what? It still looks like what it is, while the AMG from one too many angles looks like an elongated C-class ragtop.

After 12 years on the market, the GT is more competitive than when it was introduced.

In the grand Bentley tradition, the interior is lined with soft and perfectly matched hides that are as redolent as they are flawless. Bentleys don’t really have that new-car smell so much as that new Louis Vuitton–wallet smell. Tamo Ash veneers, a $1360 upcharge, are stained a yellowish hue that matches the cream-colored Magnolia leather. Gray accent leather on the doors and the top of the instrument panel is called Porpoise, but, like the other hides, it comes from land animals and not sea creatures.

Drive both back to back and it’s apparent that the Bentley is interested in taking care of you rather than taking care of everything. Despite its age, the Bentley delivers a richer and more luxurious experience commensurate with its ridiculous $272,995 price. But what really matters to us is that it’s the better car to drive.

2017 Bentley Continental GT V8 S Convertible2017 Mercedes-AMG S63 CabrioletVehiclePrice as Tested$272,995$214,525Base Price$234,525$178,325DimensionsLength189.2 in198.6 inWidth76.5 in75.2 inHeight55.2 in56.2 inWheelbase108.1 in115.9 inFront Track65.5 in64.7 inRear Track65.2 in64.9 inInterior VolumeF: 55 cu ft*
R: 31 cu ft*F: 53 cu ft*
R: 35 cu ft*Trunk, top up/down9/9 cu ft12/9 cu ftPowertrainEnginetwin-turbocharged DOHC 32-valve V-8
244 cu in (3993 cc)twin-turbocharged DOHC 32-valve V-8
333 cu in (5461 cc)Power HP @ RPM520 @ 6000577 @ 5500Torque LB-FT @ RPM502 @ 1700664 @ 2250Redline / Fuel Cutoff6250/6400 rpm6500/6250 rpmLB Per HP10.78.5DrivelineTransmission8-speed automatic7-speed automaticDriven WheelsallallGear Ratio:1/
MPH Per 1000 RPM/
Max MPH1 4.71/6.1/39
2 3.14/9.2/58
3 2.10/13.8/88
4 1.67/17.3/110
5 1.29/22.4/142
6 1.00/28.9/184
7 0.84/34.4/191
8 0.67/43.1/1911 4.38/6.9/43
2 2.86/10.6/66
3 1.92/15.8/99
4 1.37/22.2/139
5 1.00/30.4/186
6 0.82/37.0/186
7 0.73/41.6/186Axle Ratio:12.852.65ChassisSuspensionF: multilink, air springs, anti-roll bar
R: multilink, air springs, anti-roll barF: multilink, air springs, anti-roll bar
R: multilink, air springs, anti-roll baBrakesF: 15.9-inch vented disc
R: 13.2-inch vented discF: 15.4-inch vented, cross-drilled disc
R: 14.2-inch vented, cross-drilled discStability Controlfully defeatable, competition modefully defeatableTiresPirelli P Zero
275/35ZR-21 (103Y)Michelin Pilot Sport 3
F: 255/40ZR-20 (101Y)
R: 285/35ZR-20 (104Y)C/D Test ResultsAcceleration0–30 MPH1.6 sec1.6 sec0–60 MPH4.3 sec3.7 sec0–100 MPH10.5 sec8.7 sec0–150 MPH27.1 sec22.1 sec¼-Mile @ MPH12.8 sec @ 11112.1 sec @ 117Rolling Start, 5–60 MPH5.0 sec4.5 secTop Gear, 30–50 MPH2.6 sec2.5 secTop Gear, 50–70 MPH3.4 sec2.7 secTop Speed191 mph (mfr’s claim)186 mph (mfr’s claim)ChassisBraking 70–0 MPH166 ft168 ftRoadholding,
300-ft-dia Skidpad0.81 g0.89 gWeightCurb5572 lb4929 lb%Front/%Rear55.4/44.653.2/46.8FuelTank23.8 gal24.3 galRating91 octane91 octaneEPA Combined/City/Hwy17/14/24 mpg17/14/22 mpgC/D 300-Mile Trip16 mpg14 mpgConvertible TopTime to open/close20/22 sec20/18 secSound LevelIdle48 dBA42 dBAFull Throttle83 dBA78 dBA70-MPH Cruise65 dBA63 dBA
*C/D est.tested by Tony Quiroga in California City, CA
Final ResultsMax Pts. Available2017 Bentley Continental GT V8 S Convertible2017 Mercedes-AMG S63 CabrioletRank12VehicleDriver Comfort10109Ergonomics1098Rear-seat Comfort555Rear-seat Space*545Trunk Space*545Features/Amenities*10710Fit and Finish10109Interior Styling1098Exterior Styling1096Rebates/Extras*500As-tested Price*201520Subtotal1008285Powertrain1/4-mile Acceleration*201720Flexibility*533Fuel Economy*10108Engine NVH10109Transmission10106Subtotal555046ChassisPerformance*201820Steering Feel1098Brake Feel1079Handling10910Ride10108Subtotal605355ExperienceFun to Drive252118Grand Total240206204

* These objective scores are calculated from the vehicle's dimensions, capacities, rebates and extras, and/or test results.