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Audi CVT

Trendy Transmission Facilitates Shiftless Lifestyle

CVT's Coming on Strong

by Jim Bray

There's a transmission transition under way that could see conventional passenger car automatics go the way of the passenger pigeon.

The “new kid” is called the Continuously Variable Transmission (CVT) and though the technology actually dates back decades, these transmissions now appear on their way to entering the mainstream.

Continuously Variable Transmissions are said to offer the efficiency and economy of a manual transmission with the convenience of an automatic, supposedly promising the best of both worlds.

“(CVT's) offer a lighter and more compact design than conventional automatic transmissions,” says Audi Product Manager Filip Brabec, whose company is helping drive the CVT into the automotive mainstream. “They're also as fast as a manual in acceleration while being smoother and more economical than an automatic.”

While that may sound almost like a “cake and eat it” proposition, CVT's aren’t a panacea. One of the reasons they haven't caught on - yet - is that their practicality has until recently been limited mostly to smaller cars with transversely-mounted engines and front wheel drive.

Subaru pioneered the modern production CVT with an ECVT (electronic CVT) on the 1989-93 Subaru Justy but, according to Subaru's Elaine Griffin, "We stopped selling (ECVT) because the Justy was an on-demand 4WD and we wanted to concentrate on full time all-wheel drive vehicles.” She also cites reliability issues and high maintenance costs for the old ECVT, though she says the technology has advanced substantially in the past three years and doesn't rule out Subaru returning to the CVT fold.

While CVT's are currently featured on some small economy cars such as the gas/electric hybrid Honda Civic and Toyota Prius, the transmission is also beginning to appear on more mainstream vehicles such as Audi's midsize higher end performance A4 and A6 models. And more are coming.

Unlike “conventional” transmissions' fixed set of gears, torque converters, and/or other doohickeys, a CVT uses a relatively simple belt and pulley design. The belts can slide up and down from narrow to wide end of the cone-shaped pulley which allows for supposedly infinite “continuously variable” ratios.

Audi CVT shifter

The more gear ratios offered, the more the vehicle's engine can operate at its ideal speed and load – so when you tromp on the gas to peel out from a red light (not that you ever would!), the engine will stay closer to its horsepower peak for maximum “Wheee!” But with conventional transmissions only offering up to six distinct gear ratios, you're constantly passing through that peak point and have to upshift to recapture it.

With a CVT, the “gear ratios” can be varied instead of the engine RPM's. This means that, for example, an engine with peak horsepower and torque at 4000 RPM can be kept at that level much more easily than a conventional transmission that must be shifted - manually or automatically - to keep the engine in the “power band.”

One situation in which the CVT comes in handiest is on long uphill sections of highway, where traditional transmissions “hunt and peck” for the proper gear; a CVT doesn't care what the proper gear should be.

Audi's CVT works a little differently from some of the competition's whose belts are clamped and pushed from one pulley to another. Audi's “Variator,” for example, pulls - and rather than using belts it uses a chain that, according to Brabec, “Works in a manner similar to mountain bikes.”

Audi's system also offers a manual mode with six simulated gear ratios. In “automatic” mode, it uses what the company calls a Dynamic Regulating Program (DRP) to figure out the optimum gear ratio according to engine load, driver preferences and driving conditions.

CVT's are also appearing in the SUV world, the first of which offered in North America was on the 2002 Saturn VUE. Saturn parent General Motors calls its CVT the “VTi variable transmission” and claims it offers a seven to 11 per cent increase in fuel economy and 45 per cent fewer parts compared to a conventional four speed automatic.

"The VTi offers real world fuel ecomony benefits while at the same time providing an improved driving experience by not having any of the typical up and down shifts of a conventional transmission,” says Jim Ulrich, Vehicle Line Executive for Saturn. “(Saturn) products are focused on buyers looking for low cost of ownership with a fun to drive experience. The VTi contributes to this."

GM has other CVT “Ions” in the fire as well, thanks to a VTi option on the new Saturn Ion. It's also available in Europe, under the name CVTronic, on the Opel Vectra.

Then there's Nissan's new “SUV Crossover” Murano, which on the SE version will up the “pretend shifting” CVT ante with a 7 speed “manual shift” mode. And in the “pure fun” segment of the market, BMW's new MINI Cooper began offering a CVT option in late October, 2002.

Not surprisingly, driving a CVT-equipped vehicle feels closer to driving an “old style” automatic than a manual. The CVT can be a tad disconcerting to the newcomer, however, because with even the most sophisticated conventional automatic transmission you can feel a bit of a lurch when it shifts, while a CVT just keeps on a-chuggin' until the driver eventually backs off on the gas.

Driving the Honda Civic Hybrid's CVT version along Banff National Park's Columbia Icefields Parkway (where Honda's 5-speed manual Insight Hybrid had prompted an urge to get out and push) the Civic easily accelerated up the mountain passes and would hold steady uphill even in cruise control. It was smooth, quiet, felt about as powerful as a regular Civic (which, to be fair, isn't exactly a performance car either), yet still gave excellent gas mileage.

The feel of a CVT – and the accompanying lack of “engine braking,” takes a bit of getting used to but, as Car and Driver magazine pointed out in its test of Audi's 2002 A4 with CVT, the acronym could also easily stand for “Creamy, Velvety, Torquey.”

How's the public taking to the idea of a truly shiftless lifestyle? Very well, according to Audi's Brabec. “As of today (the cars) are still in short supply, ” he claims, noting that sales are hottest in sunbelt markets.

Audi plans to offer the CVT on more power train options in the future, and Korean carmaker Hyundai is also looking at throwing its weight behind the CVT, though it's being tight lipped about where, when and how.

So is there a dark cloud around this silver lining?

Well, fans of manual transmissions, who find that even a manual shift mode on an automatic doesn't cut the mustard when it comes to the fun-to-drive factor, probably won't fall in love with the CVT. As with manual shift modes on an automatic transmission, they're more fun than a “garden variety slushbox,” but it still isn't the same as rowing the shifter.

Still, if nothing else, CVT's are another choice for people interested in getting the most out of their after-tax disposable income. It may be worth doing some more research on CVT's once the lien or TitleMax loan on your current car is paid. Looking for a new vehicle with a big car loan or TitleMax title loan hanging over your head can make you think twice about how much after-tax disposable income you really have.

And that isn't a bad thing.


Jim Bray is a member of the Automobile Journalists Association of Canada. His columns are available through the TechnoFile Syndicate.

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