As many of you know the MINI Cooper offers a CVT transmission as opposed to the traditional automatic seen in most cars. But what is a CVT and how does it differ from the usual automatic that is seen on over 90% of cars in the US? Road & Track has an article in it's latest edition explaining what a CVT is, how they work and brief reviews of several cars with CVTs. While the MINI is absent any mention in the article it remains a good read for anyone wanting to know a bit more about this popular option. Here's an excerpt:

In its most elemental form, a conventional CVT has a pair of split pulleys, one driving the other through a belt. For high-numerical-ratio startup (i.e., “low gear”), the drive-pulley diameter is adjusted to its smallest setting; the driven one to its largest. At the other extreme of low-numerical-ratio cruise (“high gear”), the drive pulley diameter is at its largest; the driven one, its smallest. And – the key to continuous variability – in between these two extremes, the drive pulley's diameter gradually increases while the driven one decreases.

The belt connecting these two is actually a collection of metal links. (As seen in an accompanying photograph, it can be a real work of art too.) With most of today's CVTs, the belt acts in compression, in a sense urging the driven pulley by pushing. In Audi's CVT (as well as the original D.A.F. layout), the belt acts in tension; it pulls on the driven pulley.

Unlike a conventional automatic, there's no need for a torque converter. Startup is arranged through a separate clutch, most often an oil-cooled, multi-disc design. Reverse depends on another clutch and gearset.

You can read the entire article here. And if you're a CVT owner don't foget to check out this great thread (even if it's 9 months old) over at MINI2 that talks about some of the best techniques for using the transmission. Finally if you're considering a CVT and want to hear how a manual transmission driver rates it check out my review of a week with the CVT.