Hi bro and sis.. found this article on cvt..
CVT Benefits and Test Drives
Continuously variable transmissions are becoming more popular for good reason. They boast several advantages that make them appealing both to drivers and to environmentalists. The table below describes some of the key features and benefits of CVTs.
Advantages of CVTs Feature : Constant, stepless acceleration from a complete stop to cruising speed
Benefit : Eliminates "shift shock" -- makes for a smoother ride
Feature : Works to keep the car in its optimum power range regardless of how fast the car is traveling
Benefit : Improved fuel efficiency
Feature : Responds better to changing conditions, such as changes in throttle and speed
Benefit : Eliminates gear hunting as a car decelerates, especially going up a hill
Feature : Less power loss in a CVT than a typical automatic transmission
Benefit : Better acceleration
Feature : Better control of a gasoline engine's speed range
Benefit : Better control over emissions
Feature : Can incorporate automated versions of mechanical clutches
Benefit : Replace inefficient fluid torque converters
Cars with CVTs have been common in Europe for years. But it's taken a while for the technology to gain a foothold in the United States. The first production automobile to offer a CVT in the United States was the Subaru Justy.
Sold between 1989 and 1993, the Justy never attracted the attention of American drivers. So what's different about newer CVT-based cars -- cars like the Saturn Vue, the Audi A4 and A6, the Nissan Murano and the Honda Insight? The best way to answer that question is to take one of these cars for a "test drive." The animation below, which compares the acceleration of a car with a CVT to one without, gives you a good feel for the experience.
(sorry.. cannot download pics)
When you step on the gas pedal of a car with a continuously variable transmission, you notice the difference immediately. The engine revs up toward the rpms at which it produces the most power, and then it stays there. But the car doesn't react immediately. Then, a moment later, the transmission kicks in, accelerating the car slowly, steadily and without any shifts. In theory, a car with a CVT should reach 60 mph (100 km/hr) 25-percent faster than the same car with the same engine and a manual transmission [ref]. That's because the CVT converts every point on the engine's operating curve to a corresponding point on its own operating curve.
If you look at the power output curve for the car without a CVT, you can see this to be true. Notice that the tachometer in this situation shows the engine revving up and down with each gear change, which is recorded as a spike in the power output curve (and which the driver feels as a jolt).
CVTs are equally efficient on hills. There is no "gear hunting," because the CVT cycles steplessly down to a gear ratio appropriate for the driving conditions. A conventional automatic transmission shifts back and forth trying to find the right gear, which is far less efficient.
With all of their advantages, CVTs do have some shortcomings. In the United States, they are still trying to overcome an image problem. The Subaru Justy, for example, was known as a gutless micro-car. Traditionally, belt-drive CVTs were limited in the amount of torque they could handle and were larger and heavier than their automatic and manual counterparts. Technological advances have put CVTs in the realm of their competition -- the Nissan Murano's CVT can handle its 3.5-liter, 245-horsepower V6 engine -- but first impressions are hard to overcome.
