Clutching Success

Mechanical engineer Shreejit Changaroth and part-time car reviewer is a bit of a speed demon. A lifelong car enthusiast, he has owned numerous sporty and speedy automobiles over the decades, all featuring three pedals and an involving manual gearbox. Yet, this serial manual lover's current set of wheels is a Volkswagen Golf GTI with only two pedals; what gives?

"If I'd had a choice when I bought the car, I might probably have gotten a manual GTI, purely because Volkswagen's dual clutch gearbox was new and unknown at the time. In retrospect, I don't think I would make the same decision now," he said.

"The DSG (Direct Shift Gearbox) offers such seamless power and absolutely no drop in torque when changing gears; it really suits the GTI's character as a performance car."

In actual fact, dual-clutch transmissions (DCTs) shattered the long-held perception that manuals should be the de facto choice for sports car fans. Whereas inherent design characteristics meant manuals provided superior performance and economy throughout virtually the entire 20th Century, in the early 2000s the DCT flipped that notion on its head.

DCTs can fundamentally be thought of as two separate electronically-controlled manual transmissions contained within one housing, each with their own clutch but working as one unit; one clutch and gear set handles odd-numbered gears while the other handles even-numbered gears.

This gives the gearbox the ability to pre-select gears on the other "transmission" and clutch - when one transmission is in first gear, the other is already in second gear, and you merely have to open the clutch of one (to disengage it) and close the clutch of the other (to engage it. This allows for instantaneous gear shifts, and it not only makes acceleration faster, but smoother as well.

If that was all a bit too esoteric for you, think of it like two bricklayers building a wall; the task is completed much quicker if the first guy picks up and hands the bricks to the other to lay, rather than a single person having to alternate between picking up and then laying down bricks.

How fast can DSG go, you ask? With the next gear pre-selected and ready to go, a DSG unit can execute a gearshift in less than 40 milliseconds, or about 8 to 10 times faster than it takes for you to blink.

Not only is DSG fast, it's efficient too. Compared to a conventional automatic gearbox, Volkswagen claims up to 22 per cent better fuel economy for DSG.

Like many major automotive innovations, the dual clutch transmission's genesis was in the crucible of motorsport, having first been used in Porsche's prototype sports cars in the mid '80s. It wasn't till 2003 that this technology made it to the streets.

Volkswagen's first application of the technology was in the first Golf R32, the predecessor to the current flagship Golf R. Since then, other brands have developed their own versions in an effort to catch up.

Not that Volkswagen has been resting on its laurels however. Although it pioneered the technology in road cars, improvements to DSG are still being made with each successive generation. Even though their parts numbers remain the same, DSG gearboxes undergo continuous improvement and regularly received new parts to improve their speed, reliability and efficiency.

Ultimately, perhaps the best endorsement for Volkswagen's DSG gearboxes comes from customers themselves. "I've sampled the dual clutch gearbox of many other brands, and I feel DSG is still the best of the lot," says Mr Changaroth. "I've had my GTI for more than nine years now and I've never had any problems with it."