The Audi TT
has been one of the most influential automotive designs of the last ten years, but after four years on the market, a freshening was in order. Audi
wisely left the car's striking looks alone, concentrating instead on the powertrain, where we find a V-6 engine (the TT's first) and a clever dual-clutch manual transmission with automatic-shift capability.
The new, range-topping, engine is a narrow-angle, 3.2-liter V-6, whose 247 horsepower and 236 pound-feet of torque handily trump the high-output, 1.8-liter turbocharged four's 225 horsepower and 207 pound-feet. Of course, the V-6's power delivery is also much more linear. Audi claims the new engine will propel the TT from 0 to 62 mph in 6.4 seconds.
The TT 3.2 has upgraded brakes, firmer springs and dampers, fatter anti-roll bars, a free-flow exhaust system, larger air intakes, a more prominent rear spoiler, restyled aluminum wheels, and standard Quattro all-wheel drive, but the car's most intriguing feature is its new six-speed Direct-Shift Gearbox (DSG). Forget BMW's Sequential Manual Gearbox, Maserati's Cambiocorsa transmission, and Ferrari's F1 box. Audi's DSG is the first sequential manual that works well both in manual and in automatic mode.
The DSG (which also will see duty in the Volkswagen Golf R32) is simple to use. There is no clutch pedal; you can select gears manually by nudging the shift lever over into an upshift/downshift gate or by tapping one of two steering-wheel-mounted paddles. When the car comes to a halt, first gear is automatically selected; when the redline is reached in any given ratio, an electronic controller will trigger an upshift; when engine revs and gear requests don't match, the computer will protect the system from overload, wind-up, and shock. So far, there's nothing revolutionary here.
In the DSG's automatic mode, there is a choice between leisurely shifts (in D) and the more aggressively calibrated sport mode (S). In S, a so-called launch control feature permits some wheelspin. With the stability control system switched off, one foot on the brake, and the other massaging the accelerator, the TT V-6 will take off like a shot, revving all the way to 6400 rpm. The transmission's S mode even blips the throttle briefly during downshifts. It is possible to override the automatic program at any time with a manual shift order, but unless you are cornering hard or driving down a steep hill, the system will return to the previous setting after twelve seconds.
One of the DSG's most remarkable attributes is that it eliminates a loss of pulling power during upshifts. That's because it uses two clutches attached to separate input shafts. The inner shaft drives first, third, and fifth gears, as well as reverse; the hollow outer shaft works with second, fourth, and sixth gears. Only one gear is engaged at a time, but in preparation for the next shift, a higher or lower gear is automatically preselected. To ensure that full forward thrust is maintained even during the transition phase, the at-bat clutch disengages at the same speed and rate of progression as the on-deck clutch has when it takes over.
The true eye-openers are full-throttle upshifts, which are completed so quickly that you catch yourself checking the in-dash display to verify that a gearchange actually occurred. The brief pause between gearshifts we've encountered in sequential-manual-equipped BMWs and Ferraris doesn't happen in the TT 3.2. Instead, the car zooms forward in one long, elastic move, maintaining unbroken momentum all the way from standstill to top speed. The only variation in forward thrust is caused by a variation in revs. With no energy-devouring torque converter and no need to synchronize the engine and transmission speeds, the gearbox feels prompt and linear. Particularly in automatic mode, the DSG is appreciably smoother and quicker than previous sequential-manual transmissions. Throttle response is exceptionally sharp in every gear, and upshifts are so seamless that it's perfectly safe to execute them on slippery surfaces or in the middle of high-g corners.
On the downside, the DSG occasionally finds itself outfoxed by an unforeseen change in driving conditions. Imagine, for instance, a relatively relaxed acceleration maneuver. You're in third gear, and the transmission already has preselected fourth, but then, suddenly, a gap in traffic opens, and you put the hammer down to pass. For best results, you need a lower gear in a hurry, which means abandoning fourth and reengaging two cogs lower, into second. Instead of 300 milliseconds, this action can take as long as 900 millisecondsnot bad by conventional transmission standards but a small eternity for those accustomed to the DSG's quick responses.
Another downside is even more subjective. While driving, you'll always hear, and occasionally feel, the DSG's actuators busily changing gear ratios and alternating between input shafts whenever you lower or lift your right foot. This is no big thing, but quieter hydraulics and less mechanical noise certainly wouldn't hurt.
Because the DSG rarely puts a cog wrong, confidence builds fast; after a while, you stick the lever in D or S and leave it there, knowing full well that even the most alert driver would be hard-pressed to beat the system. Although the V-6 does not spread its torque over as wide a rev range as the turbo four, it offers more midrange grunt as well as more top-end go. Add the various chassis-related upgrades, and it's easy to see that the TT 3.2 at last has the mechanicals to back up its striking duds. Look for the TT 3.2 to arrive stateside this fall.