Road and Track - Comparison Test: Evil Twins

Merc1 · **Road and Track - Comparison Test: Evil Twins -** 02-22-2008, 03:12 AM

Many automotive manufacturers tout that their sports-car development programs begin on the racetrack. In fact, enthusiast publications, including this one, often take road-going sports cars to the track to better judge their performance credentials.

If track-focused cars are the ultimate realization of an automaker's capabilities, why not just put them on the road as is? Most would agree that there are many reasons this would be impractical: Ride comfort and day-to-day driveability, issues so critical to a road car, would never be addressed if a car were evaluated solely on its fastest lap time. Hence, automakers inevitably have to make compromises.

For the most hard-core enthusiasts willing to forgo a little civility, manufacturers are turning back the compromise dial and offering barely street-legal racers — in addition to a more road-friendly version of the same model.

So how close can a road-going sports car get in performance to a track-oriented machine born of its own DNA? With this in mind, we considered five pairs of cars to find out for ourselves: the Dodge Viper SRT10 and SRT10 ACR, the Lamborghini Gallardo Spyder and Superleggera, the Porsche 911 Carrera S and GT3 RS, the Chevrolet Corvette Z06 and ZR1, and the Ferrari F430 and 430 Scuderia.

These are all twins forged from the same basic core but with distinct purposes in mind. One is built for the street. The other is intended for the track. Unfortunately, the Corvettes and the Ferraris were not available for our test at press time, so we will give you our best assessment of the similarities and differences of these pairs from previous exposure to them.

We drove the Vipers, the Gallardos and the Porsches on the road to test their street capabilities. We then asked IMSA GTS champion and R&T contributor Steve Millen to wring them out on Willow Springs International Raceway's high-speed road course. At the end of the day, we sought to answer three questions about each higher-performing variant: What do you gain, what do you lose, and is it worth the money?

Evil Twins: Dodge Viper SRT10 vs. SRT10 ACR

LAP TIMES:
SRT10 ACR: 1:29.33 sec
SRT10: 1:32.19 sec

It is arguable how street-friendly the Dodge Viper SRT10 is in standard form. Beneath the brawny bodywork is a thunderous 600-bhp, 8.4-liter V-10 paired with a sturdy Tremec 6-speed manual transmission. Riding on a firmer suspension setup than the average sports car, the Viper can easily put the power down — and overwhelm its generous Michelin Pilot Sport tires if you're heavy-footed. With a quick 3.4-sec. 0–60-mph acceleration time, a dizzying 1.01g skidpad grip level and a 70.2-mph average slalom speed, the SRT10 blurs the line between a road car and a track car.

Still, for hard-core Viper enthusiasts who follow the motto "Race on Sunday, sell on Monday" literally, and want to spend most of their time on the track, Dodge has the perfect solution in the SRT10 American Club Racer (ACR). The ACR is equipped with the same V-10 engine and 6-speed manual transmission found in the stock Viper. The two also share the same basic interior fitment. However, that is where the similarities end.

The ACR has extensive aerodynamic improvements consisting of a carbon-fiber front splitter, fixed front dive planes and an adjustable rear wing, modifications that generate 10 times the downforce of a standard Viper. At 150 mph, the ACR experiences about 1200 lb. of downforce, distributed approximately 45 percent to the front and 55 percent to the rear.

To translate the ACR's substantial downforce into usable grip, Dodge engineers installed KW coil-over racing shocks that are adjustable for damping and ride height without removing the wheels. A new front anti-roll bar increases roll stiffness, and StopTech slotted brake rotors team with stock SRT10 Brembo calipers to slow the car. Lightweight forged aluminum Sidewinder wheels are used for lower unsprung weight. Michelin Pilot Sport Cups, barely street-legal tires with a low 80 treadwear rating, provide the ACR with excellent traction on the track.

With these focused modifications, the ACR edges out the stock SRT10 in every category in our standard road test. While acceleration runs showed only minor improvement, it is in braking and handling exercises where the racy Viper shines. Braking from 80 mph is shorter by 11 feet, steady-state lateral grip has improved by 0.11g, and improved transient dynamics through the slalom bump up the average speed by 3.2 mph.

The improvements are amplified further when Steve Millen takes both cars onto the big track at Willow Springs. With a lap time advantage of almost 3 seconds, the ACR is clearly the faster twin. Millen points out that "as with all Vipers, you must be the boss of the car, and the harder you run it, the better it is. And while the power and the gearing of the two cars feel the same, the ACR has way more grip and stability, thanks to its aerodynamics and dialed-in damping control."

Through every corner, the ACR carries more speed than the stock SRT10. Through the long right-hander of Turn 2, the ACR confidently grips the track and behaves consistently neutral with no surprises. This allows Millen to pick up the throttle earlier. There is almost a 10-mph advantage here. Down the hill through Turn 5 and over a slight crest through Turn 6, Millen barely breathes the throttle because of the ACR's tremendous grip and confidence-inspiring stability. In Turn 9, Millen comments that the stock Viper "has quite a bit of commotion over the bumps and undulations on the track." In contrast, the ACR "has less jiggle in the steering wheel because it drives smoother and you don't have to adjust as much. After the apex coming onto the straight, it feels neutral. And as soon as you get on the throttle, it just drives off, while drifting off the exit."

Overall, Millen says the ACR "works like a race car. It is balanced and well-planted through fast corners. The steering has terrific feedback. Once you get it turned, you know exactly where it is and where it is going to go and what it is going to do." Referring to the SRT10, Millen notes that you have to adjust the steering more and it takes longer to find the car's limit. Through fast corners "you are modulating the throttle more to make sure you know the rear is gonna come with you."

On the street, the stock Viper makes no pretensions of being a grand tourer. Of course, there are a few comfort amenities such as leather trim, power windows and locks, air conditioning, even a radio with a CD player. But the rumble from the V-10, the noise from the tires and the bumpy ride from the firm suspension will probably drown out any high-fidelity music or spoil a relaxing cruise. The seating position is a bit awkward for folks who are height-challenged and need to find the best compromise between reaching the pedals and not sitting too close to the steering wheel. Feature Editor Mike Monticello comments: "As a road car, the Viper suffers. The suspension is jouncy over bumps, and the footwell will roast your feet if you get stuck in traffic."

If the stock Viper is hard to handle on the road, then the ACR notches up the impracticality rating at least 10 times. It doesn't help that our ACR is a durability test car from Dodge. It has a racing seat installed for testing (production versions will have standard SRT10 seats) and a welded-in rollcage for track exercises. And there is some rear jitter under hard braking — Dodge tells us that the pads are due for replacement after extended testing just a few days before. The car is rough-riding and noisy. And it rides low enough that you have to inch your way up any driveway because of the front splitter. Fortunately, its front section can be removed for easier everyday driveability.

With the ACR, you gain a lot more performance on the track for a premium of only about $5600 (as tested). What you lose is questionable. It all depends on your tolerance for the already noisy and firm-riding character of the standard SRT10. For those who seek a Viper purely because of its track prowess, go for the ACR, because what you gain in sheer speed more than outweighs the price you pay for the road-going impracticality.

Evil Twins: Lamborghini Gallardo Spyder vs. Superleggera

LAP TIMES:
Superleggera: 1:32.47 sec
Spyder: 1:34.32 sec

The Lamborghini Gallardo Superleggera aptly plays the demonic role in the Gallardo line, not with outright performance, but with its aura. That's right, the Superleggera emits some sort of electronic/magnetic interference that prevented our test equipment from functioning within four feet of the car. Of note, we did not experience this phenomenon when we tested another Superleggera just a few months back.

As in the Spyder, the Superleggera is equipped with a 5.0-liter V-10 but retuned for better intake and exhaust airflow. The result is 10 more horsepower with the engine rated at 522 bhp and 376 lb.-ft. of torque. Thanks to several weight-saving materials, the Gallardo "light" is about 500 lb. lighter than its Spyder twin (240 lb. lighter than the standard coupe). The engine cover is made of carbon fiber and polycarbonate. The rear-quarter windows are all polycarbonate. And the underbody covering, the door panels, the rearview mirror housings, the rear diffuser, the central tunnel covering and the seat shells are all made with carbon fiber.

With virtually the same V-10 engine mated to the same 6-speed paddle-shift, electrohydraulic transmission driving all four wheels, it is amazing what a 500-lb.-lighter Gallardo will accomplish on the test track. From a standing start in full launch mode, the Superleggera reaches 60 mph in 3.4 sec., tripping the quarter-mile clock at 11.7 sec. with the speedometer sweeping past 121.3 mph. That's 0.4 sec. quicker to 60 mph and in the quarter mile than the Spyder. Even though the Superleggera is equipped with stickier Pirelli P Zero Corsa tires, it showed only a slight improvement in its slalom speed — 71.3 mph versus the Spyder's 70.6 mph. And on the skidpad, the Spyder actually beats the Superleggera by 0.01g with 0.99g.

Perhaps the difference in performance between the two is best demonstrated in the lap times around Willow Springs. Millen is able to take the checkered flag in the Superleggera almost 2 sec. faster than in the Spyder. However, with both cars, Millen admits that it took him a bit longer to get comfortable in them. He notes, "There is a trick to driving the Lamborghinis. You can't be aggressive with them."

After his first stint in the Spyder, Millen recalls, "Generally, the car's speed is limited by understeer. However, once the car gets settled in a long corner, it feels pretty good. The feedback through the steering is vague, so you never really know where the limit is." He continues, "The Supperleggera feels more nimble and more under control" when compared to the open-top Gallardo. But, he adds, "It is not a night and day difference between the two cars."

In both cars on the front straight going into Turn 1, we noticed the downshifts were a bit slow, especially when the engine seems to take longer to rev-match to the lower gearing. Millen confirms this observation, and adds: "When you are hard on the brakes and trailing deep into the corner, the ABS is invoked in the front, and then the systems starts to adjust. The rear ABS comes on, too. Then the car starts to wiggle and move around. It's unbelievable how the ABS system takes over and starts to steer the car."

Even so, the Spyder and Superleggera can speed through corners quite quickly. "Both cars are pretty stable and neutral around high-speed corners. They are well-balanced cars once into the corner. It's getting in that's the issue," Millen notes. This problem also appears coming down the hill through Turn 5: "If you're not easy with the brakes, it will move you a car's width off where you want to be. It just steers it out. It is really surprising." Around Turn 9, Millen observes, "Both Lamborghinis get into a neutral drift. The good thing is that it's not oversteering or understeering." Overall, Millen concludes both are more road cars than track cars.

While the Spyder and Superleggera may not be all-out track cars, we love their shrieking V-10 exhaust note at speed, especially coming down the front straight at Willow Springs. Lamborghinis at full song will instantly grab your attention, get your adrenaline pumping and leave your ears ringing before they disappear through the corner.

If the Lamborghini's forte is not on the track, it definitely wins top marks for its visceral driving experience on the road. Combining the mesmerizing sound of their V-10s with their dramatic angular bodies, both the Spyder and Superleggera are exotic rides that make you look and feel good. Executive Editor Douglas Kott writes in his notes: "I like the Lamborghini's V-10 for its huge thrust and sound...an angry Italian wail, somehow guttural and reedy at the same time." All of us find the e-gear 6-speed paddle-shift sluggish and the clutch takeup jerky. The brakes are hard to modulate smoothly, quite grabby when you try to come to a stop slowly.

It is a toss-up between the Spyder and the Superleggera. There is really no price difference between the two. With the Superleggera you are gaining a bit more performance on the track. What you lose with the closed coupe is the ability to work on your tan. But at the same time you gain a sleeker carbon-fiber-trimmed interior, increased structural rigidity and a rear wing that makes you look fast even when you're standing still. The nod here goes to the Superleggera.

Evil Twins: Porsche 911 Carrera S vs. GT3 RS

LAP TIMES:

Carrera S: 1:33.14 sec
GT3 RS: 1:37.09 sec

The Porsche 911 Carrera S and its evil twin, the GT3 RS, share the same famed rear-engine 911 profile. The GT3 RS stands slightly wider and lower, and features a lower lip spoiler up front and a pronounced wing on the rear deck. Probably the bright M&M-green paint job is what really sets the RS apart from the Carrera S.

But the devil is always in the details.

If you haven't checked the engine specs listed nearby, you'd know — with the first twist of the ignition key — that the Carrera S and the GT3 RS do not share the same powerplant. The S has a strong, but muted engine note. The RS spins to life with authority and makes its presence known, thanks to a thundering crackle through the exhaust. The road-going 911 is equipped with a 3.8-liter flat-6 rated at 355 bhp and 295 lb.-ft. of torque. And the more potent twin is armed with a different, race-bred 3.6-liter flat-6 capable of pumping out 415 bhp and 300 lb.-ft. of torque. Moreover, the RS's different engine fitment also calls for a 6-speed manual with slightly taller gearing in the lower ratios to take advantage of the car's higher 8400-rpm redline.

To turn the Carrera S into a worthy track racer, the GT3 RS takes the same basic front MacPherson strut and rear multilink suspension setup and firms it up with more aggressive springs and shocks. The Porsche Active Suspension Management (PASM) can already change the RS's ride character on the fly with a push of button in the cockpit. But to allow additional fine-tuning of the suspension on the track, front and rear struts have external threads and spring perches for ride-height adjustments. Further, at the rear are unique split track-control arms; metal bushings replace rubber ones for more precise wheel location at speed. Both front and rear anti-roll bars are also adjustable.

The GT3 RS is about 80 lb. lighter, thanks in part to deleting the rear seats and replacing the spare tire with a small electric air compressor and tire sealant. The Porsche Ceramic Composite Brakes (PCCBs) on the RS are 50 percent lighter than the stock rotors, reducing unsprung mass by 34.4 lb. The combination of weight savings and more horsepower equates to better acceleration numbers.

Zero to 60 mph in the RS is clocked at 3.9 sec., which is 0.2 sec. faster than the Carrera S. But as the speed builds the high-revving RS engine pulls more aggressively, thanks to a variable-volume intake system that switches over at 6350 rpm. The car pushes past the 100-mph mark with a 1.3-sec. advantage. The quarter-mile is covered in 12.1 sec. at 116.6 mph, 0.5 sec. and almost 5 mph faster than the Carrera S. In the handling department, the RS again edges out the stock S with 1.04g on the skidpad, and travels more than 3 mph faster through the slalom course. In brake tests, the GT3 RS actually needed a few feet longer to stop from 60 and 80 mph. This is perhaps due to the PCCBs not reaching their most effective operating temperature.

Of course, warming up the brakes is never a problem at Willow Springs. Right after Millen lapped the GT3 RS nearly 4 sec. quicker than the Carrera S, he noted: "The brakes are great. It got better as the laps went on." He is able to drive deeper than the Carrera S into the corners. The data showed that significant time was saved here in Turns 1, 2 and 3.

On the GT3 RS through Turn 2, Millen comments: "If you don't get into the corner quite aggressive enough, you are going to feel a little bit of understeer. With progressive throttle, the car will turn without breaking the rear away. However, too aggressive on the gas and the rear will come around in low-speed corners." To fight understeer in long corners, Millen says, "Give it more throttle, and you actually make the car more neutral."

Around Turns 8 and 9, "The Carrera feels nervous all the way through here. There is lot more movement in the suspension. The car moves laterally and vertically." Millen notes, "In the RS you can just feel the extra downforce. It is much more stable through the bumps thanks to terrific shock control. The rear is completely planted. In fact, coming out to the front straight, you can actually slide off the corner with the rear wheels spinning a bit."

Overall, Millen concludes: "The two Porsches are quite different in many ways. The GT3 RS is so well-balanced. Taking advantage of the engine's higher revs is how you are going to get fast lap times. The Carrera S is limited by its understeer and its engine's lower rev limit. And I find it's better to use a higher gear in corners because it has such a broad powerband and I don't need to be at the top of the revs."

The Porsche twins' divergent track dynamics also translate directly to their street-going nature. On the road, the Carrera is able to offer a great balance between sporty handling and supple ride quality. Kott comments: "The 911 S has a firm ride on the street, but its ride quality is very livable even for long trips. Steering feels wonderfully alive...every pavement seam and ripple feeds through the wheels into your hands. It feels precise, quick, yet not darty."

Climb aboard the RS and you'll immediately understand why track cars are not meant to be driven on the street. Editor, R&T Specials, Andy Bornhop writes: "On the road the RS demands some sacrifice. It's loud inside and has a very firm ride. And you have to pick your driveways carefully (and proceed slowly) to avoid scraping the chin spoiler."

Even though the Carrera S and the GT3 RS are born of the same 911 DNA, these two cars couldn't be more different in their intended purpose. The Carrera is perfect for the road. The RS is perfect for the track. In this battle of evil twins, is it better to be "the master of one" or the "jack of all trades"? So take your pick. If the racetrack is where you want to live, the $50,000 jump in price from the Carrera S to a GT3 RS may be worth it. But if you are like most of us, where our day job calls for driving mostly on public roads, go for the Carrera S. You'll feel more comfortable, and occasionally you can still satisfy that racing itch and squeeze in a few weekend track days.

Evil Twins: Ferrari F430 vs. 430 Scuderia

Okay, you're not Michael Schumacher and this isn't a Formula 1 Ferrari, but the imagery works.

You're humming down the road, strapped into a carbon-fiber shell seat that has a grip on your backside. There's a V-8 behind you in a bay of carbon fiber and with an adrenaline-spiked exhaust note. As the engine spins toward redline, a series of red lights at the top of the steering wheel Pac-Mans to the right. Tap the right-side shift paddle and in a fraction of second you're up a gear.

Raucous is the word...

During Ferrari's early years many of its road cars were warmed-over race machines. Subtract horsepower for tractability, spiff up the interior and send it home. Now Maranello has done the opposite to create the evil twin of its mid-engine V-8 sports car, transforming the F430 into the 430 Scuderia.

What did they do?

Trimmed some 220 lb. down to a claimed 2975-lb. curb weight. The easiest place to see poundage lost compared with the F430 is inside the Scuderia. Typical of Ferrari, it doesn't look like they so much subtracted anything, but made the surroundings look even cooler, simpler, more like a race car. The instrument panel is little changed, but much of the trim is now carbon fiber. Floormats are out in favor of aluminum plating. Missing sill covers reveal beautiful welds of the aluminum space frame. The seats are shaped like works of art.

There are exterior differences. There's the same coupe shape but the detailing is squarer-cut, more aerodynamically efficient and businesslike. The Scuderia sits a bit lower than the F430, more of a tough-guy stance.

Ferrari engineers made the exhaust sound from the 4.3-liter V-8 even more feral, also turning up the power by improving engine breathing. Horsepower is stretched by 20 to 503. Torque improves by just 4 lb.-ft., but the upper reaches of the curve are fattened versus the F430's powerband.

The F1 gearbox has shifts slimmed to 65 milliseconds, and with the help of E-Diff to distribute torque plus F1-Trac, the 430 Scuderia has the flat-handling demeanor of a race car, with carbon-ceramic brakes to slow it.

Where the F430 is a highly civilized supercar that can be pushed to extremes, the 430 Scuderia is already at the sharp end, able to lap Ferrari's Fiorano test track as quickly as an Enzo. Yet it has a second nature that doesn't object to being driven like its not-so-evil road-going twin.

Evil Twins: 2009 Chevrolet Corvette Z06 vs. ZR1

The Corvette is revered around the world as America's sports car. Over the generations Chevrolet has spawned some specialized models that added to the already potent performance-car's cachet. The Corvette Z06 is that model, with a 7.0-liter, 6500-rpm-redline V-8 dumping a thunderous 505 horses on its aptly named Goodyear Eagle F1 Supercar tires. But apparently that wasn't enough for the boys at GM. They don't just want to compete with the likes of Aston Martins, Ferraris and Porsches; they want a car that'll catch 'em, slap 'em around, call 'em Suzy and then go on to lap 'em. That's the newest ZR1, the most menacing Corvette ever sold.

Before you get your hopes up too high, I'll tell you now: We haven't driven the ZR1 — yet. That's not going to happen until the end of the year. The estimated performance numbers are subject to much debate. Nevertheless, the Z06 has what it takes to be the ultimate track car, as that's its intended function. The ZR1 is developed from the Z06, using its aluminum structure as a starting point. Its engine, transmission, differential, brakes, shocks and springs are all unique. For a more thorough look at the ZR1, see our February 2008 issue.

The heart of the ZR1 is the LS9 6.2-liter supercharged V-8. It's expected to have 620 bhp, or possibly more. Overall, the engine puts out 20 percent more power and torque than the already ferocious LS7 from the Z06! The car has gained roughly 200 lb., even though it employs carbon-ceramic brakes and lightweight carbon-fiber bodywork. The extra weight will hurt performance a bit, but some will be gained back with specialized Michelin tires. We expect slalom and skidpad performance to be affected most.

Corvette ZR1 engineers have said that the Z06 will remain the favorite for track enthusiasts, but for the ultimate get-up-and-go, the ZR1 is the ticket. To make it more confusing, the ZR1, which features Magnetic Ride suspension, will almost certainly have more comfortable ride motions. But when set to Sport, it will be as firm as the Z06. The MR system has the added benefit of helping to control pitch and yaw during acceleration and braking. Of particular interest is the system's launch-control strategy that lets the car squat to aid weight transfer and improve traction.

The Z06 is already the evil twin of the standard LS3 Corvette, but it's not quite the Blue Devil we expect the ZR1 to be. We'll tell you more when we get our hands on the beast.

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