For nearly 50 years, Motor Trend has pitted America's best sports car against Germany's, but never has the competition been this fierce. In fact, the last time we did it, the Stars and Stripes emerged tattered and torn. That was four years ago. Now, everything's the same yet completely different.

Take the cars. Yeah, it looks like the same 911 Carrera S, sprayed blue rather than yellow, but this "991.2" Carrera S is a werewolf in wolf's clothing. The Porsche's flat-six engine is now turbocharged and produces 20 more horsepower and 43 more lb-ft for 420 and 368, respectively. It features an optional rear-steering system, standard PASM active chassis control, an updated suspension and dual-clutch transmission, and a refreshed interior. The extra gizmos added about 100 pounds, but the extra grunt slightly improved the power-to-weight ratio.

Then there's the Corvette Grand Sport. There's no mistaking this car for the one the Porsche shellacked. Based on the 2014 model year C7 redesign, it starts from the vastly improved Stingray and outfits parts from the equally improved Z06. The LT1 V-8 gains 24 hp (460) and 37 lb-ft (465) over the old LS3.

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The frame is now aluminum rather than steel. It added carbon-ceramic brakes and an electronically controlled limited-slip differential. It brings the high-tech factor, too, with standard magnetorheological adaptive dampers, the Z06's Stage II aerodynamic aids, and barely legal Michelin Pilot Sport Cup 2 tires. Like the Porsche, all these gee-whiz items added weight, to the tune of about 90 pounds, but the Grand Sport's power-to-weight ratio has also improved. If there were a ribbon for most improved, the Corvette would win in a landslide. But is it enough?

Each time we do this contest, we prepare for the onslaught of correspondence written in capital letters declaring the Corvette the outright winner, simply due to its price advantage. Yes, the Porsche is expensive. It's a fact of life. We've argued in the past the 911's superiority as a vehicle justifies the price difference. Your bank account may vary. Now, the Carrera S is even more expensive with a six-figure starting price of $104,450, an increase of about $7,000. But the Grand Sport has also has taken a big leap with its base price climbing $10,000 to $66,445.

What's interesting is that both test cars are packing tens of thousands of dollars in options. The Corvette carries just over $25,000 worth of extras, and the Porsche packs about $36,000 onto the price. In both cases, most of the extra coin goes to performance upgrades. There's no order sheet advantage here; each is the highest-performance variation of the base car. Yes, we would've preferred a 911 with a manual transmission, but Porsche couldn't provide one with all the optional performance upgrades.

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You may notice a pattern in what follows. These two trade blows the way siblings trade insults. On paper, at the test track, and in the real world, they swap advantages. It's a constant conversation of "yeah, but" as we try to sort out which is the better car.

Start with the test data. The Corvette is more powerful, but the Porsche is quicker. Its 63 percent rear weight bias and confoundingly quick-shifting transmission allow it to launch harder and deliver uninterrupted acceleration. Its 3.1 seconds to 60 mph is supercar quick and mind-boggling for a car with less than 500 hp and rear-wheel drive. The manually shifted Corvette's 3.9-second sprint is great, but it won't ripple your cheeks. And the Corvette's 12.2-second quarter-mile pass at 116.1 mph looks impressive until you see the 911's 11.5-second pass at 120.5 mph.

The Porsche is lighter, but the Corvette stops shorter. Credit those gumball tires because the Porsche's brakes are bigger. The Corvette stops in a retina-detaching 90 feet to the 911's 97.

The Chevrolet Corvette Grand Sport and Porsche 911 Carrera S trade blows the way siblings trade insults.

In steady state cornering, the Corvette sets a new production car record of 1.18 average g. The Porsche manages a quality runner-up 1.05. The Porsche's advantage slips on the figure eight, though, where the manually shifted Corvette still manages to dominate. The 911's 23.1-second lap at 0.91 average g is supercar quick, but the Corvette posts a nearly record-breaking number. Its 22.3-second lap at 0.96 average g ties it with the Corvette Z06 and Viper ACR for second behind the mighty Porsche 918. Test guru Kim Reynolds is convinced an automatic Corvette could post an even better lap time with quicker upshifts. That's a double-edged sword, though, because as quick as the automatic Corvette is at upshifting, its downshifting is ponderous and glacial.

On and on it goes like this. We venture off into the canyons only to find the same dichotomy. The two rivals drive wildly differently, but any flaw you can point to on one car can be negated by a demerit with the other.

The Porsche is engineered the way a modern Formula 1 or Le Mans prototype car is designed. It's all about maximizing every last bit of the performance envelope as efficiently as possible. Making the driver's heart race is important, but it comes second to outright performance. Stuttgart's finest is incredibly quick and confident in a canyon—never unruly or intimidating. Want to drive blindingly fast? Ist einfach, baby.

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The Corvette, in contrast, is skydiving with your chute on fire. It's passionate driving, the car demanding your full attention but delivering an adrenaline rush you will tell your grandkids about someday. You grab it by the scruff of the neck, and it grabs you right back. Despite that fearsome attitude, it's as brilliant in the corner as the Porsche.

It's how these cars behave in those corners where the two stand apart. The Corvette's steering is wickedly quick and precise, and its grip is effectively endless. You would have to be a world-class thickhead to induce understeer. Once you're acclimated to the car, you can still enter a corner at a speed you think is too fast, and the front end will respond the same as if you were crawling. Mid-corner, you can keep steering tighter and tighter until you drive yourself right off the inside of the turn. It simply won't let go. That sort of over-engineering once was the provenance of Bavaria, but Chevrolet has shown America can create cars that stay glued to the corner.

The Grand Sport also partially exorcises a long-lived Corvette demon—its tendency to snap-oversteer at the limit. Sure, it'll still do it, but it approaches the limit more gradually and predictably, and it no longer snaps back the other way when you correct it. This is the best-driving Corvette yet built.

"You genuinely have to recalibrate your driving for it," Jason Cammisa says. "You can't use all of this grip on the road, because in most circumstances the limiting factor isn't grip. It's your sight-lines. The mid-corner steering response is unbelievable. There is no understeer." Jonny Lieberman calls it "borderline magic."

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The Porsche is Niki Lauda to the Corvette's Dale Earnhardt. Forget the drama. Focus on the driving. Bumps that unsettle the Corvette's chassis (though never breaking traction) magically disappear under the 911. The Porsche's throttle response, thanks to an ingenious anti-lag system, is instantaneous at speed and better than the naturally aspirated Corvette's. This may be the first time a turbocharged engine's response bests that of a naturally aspirated engine. Thus endeth the credo, "There's no replacement for displacement. "The way the Porsche exits a corner is more impressive. Far earlier than seems wise, you can roll into the throttle, straight to the floor. Forget the eggshells under your right foot. Forget oversteer. Forget understeer. Forget the 37/63 rear weight bias. Go ahead. Mash it. The 911 digs in and flings you out of the corner.

Let's get to the flaws. The Corvette's gearing, as always, is too tall—in hopes that its endless torque will save the day. But it makes the 911 feel quicker in the midrange, where the Carrera's turbocharged engine is already at peak torque while the Corvette's is still climbing. The 911, meanwhile, has picked up some disappointing mid-corner understeer. On most cars, you wouldn't call this significant, but it's frustrating. Where the Corvette never stops turning, you can feel the exact limit of the 911's front tires, the exact point at which it won't go around the corner any quicker even though the chassis is laughably up to the challenge. "There's not much you can do about the understeer in the middle of the corner except drag brake to induce rotation," Cammisa says, "but it's throttle-adjustable on the way in and out."

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As daily drivers, the differences are starker. The 911 is the superior example. It's more comfortable, its ride is more compliant, and its interior is substantially nicer. But the Corvette has a standard targa roof and gets far more attention with its widebody kit. Porsche has done a remarkable job of making its turbocharged engine sound nearly as good as the naturally aspirated one, but the Corvette's big V-8 conjures the dark lord of guttural thrust that makes teenagers of men. Then again, the entire Porsche assembly line would be flogged if its interior came unglued like the Corvette's fancy diamond-stitched Alcantara headliner did with just 3,000 miles on the clock. Also, for $90,000, those stripes on the Corvette's front fenders ought to be painted on, not cheap-looking stickers. This is not some Civic street-racing night in the Valley, after all.

"I dream of a day when the perceived build quality of the Corvette will not hurt its sales," Lieberman says. "I don't know what it would take to make a Corvette feel as solid as a Porsche, but here's hoping one day that negative is off the table."

Forget the eggshells under your right foot. Go ahead. Mash it.

Cubic dollars, probably. One could imagine what that $38,000 base-price difference could do for the Corvette's interior. There's a reason the Porsche is so expensive, and it's not all profit and badge. There's also no arguing the Corvette is an incredible performance bargain. But as with all bargains, it comes with a catch.

As Cammisa points out, though, the 911 comes with its own catch. "Not exactly thrilling in normal driving, but this is, when rated as an automobile, an excellent car," he says. "This 911 offers shocking levels of performance for its engine size and output, and indeed it would make a comfortable, easy-to-live-with daily driver. But it's missing a lot of the excitement that would make it a great occasional-use sports car."

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Lieberman disagrees with the stereotype of German clinical precision. "The 911 is docile around town," he says. "I heard some people—Cammisa—describe it as boring, but I don't think that's fair. It's just calm. Boring is dull. The Carrera S isn't dull. It's bored. It's waiting for you to twist that knob on the steering wheel and go get some." Here again, Lauda vs. Earnhardt. The 911 is cool, calculating, and methodical. The Corvette is shock and awe. Two very different ways of achieving the same stellar performance.

"I think that the issue of which one of these two cars is better partly comes down to a head-versus-heart battle," Lieberman says. "Logically speaking, I think the 911 makes great sense and would easily satisfy all of my everyday needs. The only problem is that I'd be daydreaming of driving the Grand Sport while I'm out grocery shopping in the Porsche."

Our hearts and minds were at odds. It seemed impossible for the testing group to reach a consensus, so we decided to let the racetrack settle it. Given we couldn't outrun each other on the road no matter who drove what car, we expected a nail-biter of a track battle. We weren't disappointed. The Corvette arrived at Willow Springs International Raceway's Big Track with advantages in power, aerodynamics, and lateral grip, and the 911 boasted quicker acceleration and a quicker-shifting transmission.

In the hands of Randy Pobst, the 911 ran a 1:27.10. The Corvette: 1:26.28. Yes, were the Porsche offered with stickier tires, it could have made up ground, but an automatic in the Corvette could have improved its time, as well. Although some might see the track-focused Corvette's win as a foregone conclusion, we shouldn't overlook that the 911 put in one hell of a lap for a daily driver on summer tires.

They may have entirely different personalities, but few cars are so closely matched, their strengths and weaknesses so balanced, performance equals on the street and nearly so on the track. It's the toughest decision we've made in a long time. But when the question is asked, "Which is the better sports car?" the answer is, by a 0.82-second margin, the Chevrolet Corvette Grand Sport.

2017 Chevrolet Corvette Grand Sport 2017 Porsche 911 Carrera S POWERTRAIN/CHASSIS DRIVETRAIN LAYOUT Front-engine, RWD Rear-engine, RWD ENGINE TYPE 90-deg V-8 alum block/heads Twin-turbo flat-6 alum block/heads VALVETRAIN OHV, 2 valves/cyl DOHC, 4 valves/cyl DISPLACEMENT 376.0 cu in/6,162 cc 181.0 cu in/2,966 cc COMPRESSION RATIO 11.5:1 10.0:1 POWER (SAE NET) 460 hp @ 6,000 rpm* 420 hp @ 6,500 rpm TORQUE (SAE NET) 465 lb-ft @ 4,600 rpm* 368 lb-ft @ 1,700 rpm REDLINE 6,600 rpm 7,400 rpm WEIGHT TO POWER 7.5 lb/hp 8.0 lb/hp TRANSMISSION 7-speed manual 7-speed twin-clutch auto. AXLE/FINAL-DRIVE RATIO 3.42:1/1.64:1 3.59:1/2.23:1 SUSPENSION, FRONT; REAR Control arms, transverse leaf spring, adj shocks, anti-roll bar; multilink, transverse leaf spring, adj shocks, anti-roll bar Struts, coil springs, adj shocks, anti-roll bar; multilink, coil springs, adj shocks, anti-roll bar STEERING RATIO 12.0-16.4:1 12.5-15.0:1 TURNS LOCK-TO-LOCK 2.5 2.5 BRAKES, F; R 15.5-in vented, drilled carbon ceramic disc; 15.3-in vented, drilled carbon ceramic disc, ABS 16.1-in vented, drilled, carbon-ceramic disc; 15.4-in vented, drilled, carbon-ceramic disc, ABS WHEELS, F;R 10.0 x 19-in; 12.0 x 20-in, forged aluminum 8.5 x 20 in; 11.5 x 20 in forged aluminum TIRES, F;R 285/30ZR19 94Y; 335/25ZR20 99Y Michelin Pilot Sport Cup 2 ZP 245/35ZR20 91Y; 305/30ZR20 103Y Pirelli P Zero N1 DIMENSIONS WHEELBASE 106.7 in 96.5 in TRACK, F/R 63.5/62.5 in 60.7/59.8 in LENGTH x WIDTH x HEIGHT 176.9 x 77.4 x 48.6 in 177.1 x 71.2 x 51.0 in TURNING CIRCLE 37.7 ft 35.1 ft CURB WEIGHT 3,464 lb 3,353 lb WEIGHT DIST, F/R 50/50% 37/63% SEATING CAPACITY 2 4 HEADROOM, F/R 37.9/— in 37.7/32.2 in LEGROOM, F/R 43.0/— in 42.2/27.1 in SHOULDER ROOM, F/R 55.0/— in 51.3/47.9 in CARGO VOLUME 15.0 cu ft 5.1 cu ft TEST DATA ACCELERATION TO MPH 0-30 1.7 sec 1.2 sec 0-40 2.3 1.7 0-50 3.2 2.4 0-60 3.9 3.1 0-70 4.8 4.0 0-80 6.1 5.2 0-90 7.4 6.4 0-100 8.8 7.9 PASSING, 45-65 MPH 1.7 1.5 QUARTER MILE 12.2 @ 116.1 mph 11.5 sec @ 120.5 mph BRAKING, 60-0 MPH 90 ft 97 ft LATERAL ACCELERATION 1.18 g (avg) 1.05 g (avg) MT FIGURE EIGHT 22.3 @ 0.88 g (avg) 23.1 sec @ 0.91 g (avg) TOP-GEAR REVS @ 60 MPH 1,250 rpm 1,700 rpm CONSUMER INFO BASE PRICE $66,445 $104,450 PRICE AS TESTED $92,060 $140,465 STABILITY/TRACTION CONTROL Yes/Yes Yes/Yes AIRBAGS Dual front, side, head Dual front, side, curtain, knee BASIC WARRANTY 3 yrs/36,000 miles 4 yrs/50,000 miles POWERTRAIN WARRANTY 5 yrs/60,000 miles 4 yrs/50,000 miles ROADSIDE ASSISTANCE 5 yrs/60,000 miles 4 yrs/50,000 miles FUEL CAPACITY 18.5 gal 16.9 gal EPA CITY/HWY/COMB ECON 16/25/19 mpg 22/28/24 mpg ENERGY CONS, CITY/HWY 211/135 kW-hrs/100 miles 153/120 kW-hrs/100 miles CO2 EMISSIONS, COMB 1.02 lb/mile 0.80 lb/mile RECOMMENDED FUEL Unleaded premium Unleaded premium * SAE certified