as you increase the number of speeds, you approach a continuously-variable-transmission design (which is equivalent to an infinite number of speeds), but this is still tricky to design, although Audi has a good implementation. And Audi has found out that people still want the "stepped" feel of a traditional autobox with discrete gear ratios; they therefore designed their CVT to simulate this.

another truly revolutionary design is the direct-shifting-gearbox design of Audi, which pre-selects the next gear (up or down), resulting in quick and seamless gearchanges, with no interruption in the power delivery.