Audi Sport’s RS3 and TT-RS: The same engine but very different cars  9/17/2017 1:00:07 PM   Jonathan M. Gitlin

We usually pay for our own travel expenses, but in this case Audi provided flights to New York City and two nights' accommodation. While we have paused all sponsored travel opportunities at this time, this event took place in July before that moratorium began.

SALISBURY, Conn.—Success on the racetrack doesn't sell cars like it used to. That said, plenty of car companies still go racing. And it's not just a marketing exercise; it remains an engineering one, too. Competition breeds ingenuity, and a motorsports department is like a skunk works that can add a halo to a mundane car or turn an already good one all the way to 11. BMW has M. Mercedes-Benz has AMG. Volvo (yes, that Volvo) has Polestar. And Audi has Audi Sport.

We were quite smitten with Audi Sport's handiwork when we tested the R8 this summer, but, given that car's bones, it was bound to impress. Finding out what Audi Sport's engineers can do with more modest beginnings was the reason we headed up to Lime Rock Park, a scenic race track a couple of hours north of New York City. Well, that, plus we were promised a hot lap with racing legend Hans Stück in the driver's seat.

The TT-RS and RS3 share more than just Audi Sport's coveted RS (for RennSport, "racing sport" in English) badge. Both use the same MQB architecture. They even use the same 2.5L TSFI engine. But after a day spent lapping them on track and driving them on the street, we were somewhat shocked at just how different each car turned out to be. One completely blew our socks off, while its sibling underwhelmed in comparison. To find out which was hot and which was not, buckle up.

Our mission for the day was to put both cars to the test on track at Lime Rock Park in Connecticut.
Enlarge / Our mission for the day was to put both cars to the test on track at Lime Rock Park in Connecticut.

A five-cylinder family tree

MQB—or modular transverse toolkit—is the starting point of every transverse-engined car built under the VW Group umbrella since 2011. It's a common architecture, which means it uses standardized and interchangeable parts but with a constant engine and front axle position. What it's not is a common platform, so MQB cars can (and do) vary wildly in size and shape.

These two cars share an identical five-cylinder heart, though. The "straight five" layout is uncommon, but there are some advantages. Each cylinder in a four-stroke engine fires once for every two rotations of the crankshaft. So in a boring old four-cylinder motor, that happens every 180 degrees; as one piston reaches the end of its power stroke the next begins, and so on. When you start to add more cylinders, the power strokes have to overlap—with five cylinders, the engine fires every 144 degrees, providing 36 degrees of overlap. The result is a smoother delivery of power.

However, the same is true for a straight six, which is also inherently balanced and, so, free of vibrations that afflict inline engines with fewer pistons. Engine snobs, therefore, point to the straight six as the ideal inline layout for internal combustion, even though they are mostly out of vogue. The issue is one of length; the need to fit crash structures means few can spare real estate under the hood to mount one, particularly when a V6 has just as many pistons and is 50-percent shorter. But a straight five will fit, transversely, between the front wheels of a car.

It's a choice from left field but one heavy with meaning here. Audi's badge has four rings, but its reputation was built on five cylinders. The Quattro coupé arrived in 1980, powered by a turbocharged (longitudinal) five. Coupled with all-wheel drive, it was a capable all-weather performance car, but its exploits in motorsport conferred legendary status. Drivers like Michèle Mouton, Walter Röhrl, and Stig Blomqvist won many rallies in Quattros, creating a legion of fans in the process.

Here in the US the rally cars made less of an impact, although Quattros did win at Pikes Peak five times in the six years between 1982 and 1987. In 1988, that distinctive five-cylinder engine note would be heard in the highly competitive Trans-Am series. Hans Stück, Hurley Haywood, and Walter Röhrl used their 507hp Audi 200s to good effect, winning eight of the 13 races. Stück took four wins, Haywood the championship, and in response the SCCA banned all-wheel drive and foreign engines from the series. So the following year, Audi switched its attention to IMSA's GTO class, bolting on an even bigger KKK turbocharger along the way. With 720hp in his Audi 90 Quattro, Stück blitzed seven of the 12 races Audi entered.

The engines that powered Stück and co. on to glory share nothing with that of the engine of TT-RS and RS3 beyond cylinder count and firing order (1-2-4-5-3 for those who care). The new engine really is brand new, replacing the same capacity motor that powered the previous generation TT-RS and last year's RS3. Many of the changes involved weight reduction.  An aluminum engine block, magnesium oil pan, and hollow crankshaft all conspire to save 57lbs (26kg).

Both direct and port injection are employed, the latter in cases where it helps low-speed emissions. Variable valve timing does its bit, too, altering the duration the exhaust valves are open for better fuel efficiency at low speeds versus when hard acceleration is the order of the day. The BorgWarner turbocharger has had its wick turned up; boost is now 19.6psi (1.35bar) and compression is 10:1. The net result of all this is a compact but powerful engine, providing both cars with 400hp (294kW) and 354lb-ft (480Nm).

Listing image by Audi

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The poor TT, now in its third iteration, has always suffered somewhat from an unfair reputation of putting style first. And the regular TT is very stylish and also most definitely not a track car, something impressed upon us repeatedly before Audi let us drive one at the Circuit of the Americas in Texas back in 2015. Well, forget what you know about that—the TT-RS is most definitely a track car.

The previous TT-RS was a perfect example of some motorsports halo applied to a model nearing the end of the line. It even took a Facebook petition to convince Audi of America to bring 800 over here. This TT-RS arrived much sooner in the product cycle, and Audi hopes to sell a lot more despite the $64,900 starting price. True, it's $20,000 more than the base TT, but you do get a lot of extra stuff for that cash. For one thing, it looks meaner than any TT before it, those wings and vents and scoops giving the car a touch of menace.

Obviously you get that 400hp engine, which is almost double the regular TT. Audi Sport has been busy with the rest of the car as well. The Haldex all-wheel drive system is now quite happy to throw 100 percent of the engine's torque at the rear wheels. That can happen pretty fast, the car knowing when to preload the multi-plate clutch for faster response times. Audi's torque vectoring rear differential is also fitted. The dual-clutch transmission has seven ratios, versus the six you find in more pedestrian TTs. The brakes have been super-sized, now 14.6 inches (370mm) at the front—2.3 inches (58mm) bigger than the base car, with eight-piston calipers.

The red TT-RSes you see in the photos and our video are even less compromising, thanks to the optional $6,000 Dynamic plus package. This swaps the iron front brake rotors for ones made of ceramic, with less mass and more resistance to fade. The adjustable suspension's magnetorheological dampers are replaced with a stiffer, track-optimized setup using conventional valved shocks. Top speed is raised to 174mph (280km/h), up from 155mph (250km/h), and the package also throws in a carbon fiber engine cover, OLED brake lights, and tire temperature and pressure monitors for good measure.

All of that techno-wizardry is fine and well, but there's always a danger that the end product feels cold or anodyne. No such worries exist here. The TT-RS shined, brightly, on both road and track. You get a plenty quick car for your money, one that can despatch 60mph in just 3.6 seconds.

To show off the car's launch control—and perhaps to encourage some healthy competition among the assembled journalists—Audi had set up a 0-60 feet test for us. It was an ample demonstration of how the car can send all its power to the rear wheels, for they do all the hard work when launch control is engaged.

For the record, I would have taken top honors, but Autoweek's Jake Lingeman's best time involved a little bit of a run-up to the starting line. (Racing drivers have an excuse for every occasion, and that's mine. This is the third time this year that I've managed to not quite win one of these, coming second in the Lane Motor Museum's gymkhana and only fourth-fastest in the Chevy Bolt Autocross.)

As a road car, the TT-RS comes off feeling unflappable. It is blisteringly fast, particularly in second and third gears. In Dynamic mode, power delivery becomes more rear-biased, although Audi Sport's Head of Technical Development, Stephan Reil, did tell us that when you're just driving straight ahead, the power is almost sent to the front wheels.

On track, it just shined, in its element on the tight confines of Lime Rock's seven turns. It's more nose-heavy than rivals like the BMW M2 or Porsche 718 Cayman S, carrying almost 60 percent of its weight over the front axle. You would expect that to be the recipe for plenty of understeer, but, between the sport suspension and the car's ability to torque vector, that simply wasn't the case.

The best test of the car's agility was through the Up Hill chicane. Accelerating hard down No Name Straight, you have to shed 50-60mph before turning into the right-left-right sequence that follows. Accelerating up through the chicane, you really feel the way the car redistributes power, front to rear and side to side. This was most apparent when Hans Stück took us for a ride. The 66-year-old may no longer race professionally, but he has lost none of his speed or flair behind the wheel, and my subsequent laps were surely a little faster after the impromptu masterclass. (My lap in the video was actually earlier in the day, so you won't see any evidence of that when you watch it.)

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Unfortunately for the $54,900 RS3, it did not shine in comparison with its five-cylinder sibling. Under its skin the RS3 is packed with just as much go-fast technology as the TT-RS. Same 400hp engine. Same seven-speed dual-clutch gearbox, with close-stacked ratios lower down the order and a longer 7th for cruising. There's the same torque vectoring rear differential, the same adaptive suspension, and the same gigantic front brakes.

The A3 sedan on which it's based isn't Audi's best-looking car, and visually the RS treatment only amounts to slightly different bumpers, a little trunk spoiler, and oval exhaust pipes. The light tweaks continue on the inside. The A3's cabin is now starting to feel rather dated, particularly when parked next to the TT, which is a riot of interesting surfaces, materials, and design touches. The view out the front is slightly better in the sedan, its A pillars causing less of a blind spot than the low-slung coupé. But the driving position isn't as good, the seats don't grip you nearly as well, and the TT-RS' steering wheel feels much better in hand.

Like the red TT-RSes, the red RS3s in Lime Rock's pit lane were specced with the Dynamic plus package—here only $4,800. It doesn't include OLED tail lights, but the rest of it—the 174mph top speed, the fixed sports suspension, ceramic brakes and so on—is the same.

Still, there are differences. The RS3 is a much heavier car—3,593lbs/1,630kg vs. 3,306lbs/1,500kg)—so straight-line performance is a little blunted, giving up 0.3 seconds in the dash to 60mph. It's a bigger car, too, with five inches (127mm) more between front and rear axle. However, it has a narrower front and rear track (the distance between wheels on the same axle), and, perhaps most critically, it wears slightly narrower tires at the rear. (If you don't spec the Dynamic plus package then all four tires are narrower than the TT-RS'.)

The dynamic consequences of these differences is most easily noticed on track. In a controlled environment you can explore much more of a car's performance envelope, and here we discovered the RS3's approach was simply more vague than the more hardcore TT-RS. There was more roll in the corners, and it was more nervous under braking as the weight transferred forward, taking rear grip with it.

That's not to say the RS3 was outshone in every department. When you're not in maximum-attack mode and are more interested in cruising along with the flow of traffic, the RS3's ride was much better. And it's a much more practical car, complete with rear seats (and even doors that provide access to them). It does give up a couple of cubic inches in luggage capacity to the smaller car, though. Both should be equally reliable. These days the brand finds itself among the sharp end of reliability surveys, and both Audi Sport cars went through punishing durability testing at the Nürburgring Nordschleife.

Audi Sport's Stephan Reil told us that the point of testing at the 'Ring isn't to optimize a car to perform well there—although he did say the TT-RS should complete a lap in 7 min 48 seconds in the hands of an ace. Rather, the point is to give the car and its components a real workout. "One mile of the Nürburgring is the same as nine miles of normal road stress," Reil explained. Audi Sport conducts two 5,000-mile durability tests during development, one with a mule at the beginning of the process and the second just before production is signed off.

Perhaps it's unreasonable or unfair to complain that the cheaper car isn't as accomplished as the model that costs $10,000 more. But Audi brought both models along, and we all drove them back to back. As such, it's therefore hard to avoid making direct comparisons.

Our verdict

After a full day's driving, we were really, really impressed with the TT-RS. In fact, it shone so brightly that it rather overshadowed the RS3. As an illustration of how a common architecture and even a shared powertrain can still result in two very different vehicles, this experience was illuminating. The RS3 is a competent sports sedan and, of the two, a far more practical vehicle. It's also significantly less expensive than the coupé and probably more acceptable as a daily driver.

On the other hand, many may find the TT-RS a little too hardcore as a daily driver. Its performance is honestly not that far behind the mighty R8, particularly on the road, but even on a twisty circuit like Lime Rock. That performance is definitely more accessible to drivers of everyday skill than a mid-engined V10 supercar. It's certainly a match for similarly priced sports cars from rivals like Porsche and BMW and proof that a TT doesn't mean style over substance. It might not be cheap, but if you happen to have $70,000 burning a hole in your pocket, you could do a lot worse than a TT-RS.

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