A4 is Audi's small sedan. The A4 multitronic derives its name from its continuously variable (CRV) transmission -- trademarked by Audi as "multitronic." It replaced the well known Tiptronic transmisson on Audi's front wheel drive cars. While it's gearing continuously changes in response to its environment, it has a manual mode where the driver can select the gears. But since it has no fixed gear ratios, the manual mode is a simulation mode. Being new and very complex, neither the multitronic transmission or the A4 bearing its name are without problems.
Traditional manual transmissions have a mechanically positive drive connection as soon as the clutch is engaged. It took some time to work the bugs out on traditional automatic transmissions --- to provide the driver with response at the time, even with a clutchless idle. The multitronic seems to suffer from this since it can have a hesitation or delay when first accelerating.
One of the more common complaints about the multitronic is lurching or jerking under acceleration, especially when the car first begins to accelerate. These problems are sometimes caused by the digital input to the transmission. This car is not controlled by a series of gears -- a computer tells the continuously variable transmission what gear ratio it should have. The problem is sometimes solved when the care goes through a "drive cycle," or is shut completely down, turning the computer off, then restarted and resetting the computer.
It's Very Different
Different isn't necessarily a problem. If you get used to it, the multitronic may be very rewarding to drive. But it does take some getting used to. Most cars have to match their transmission to a specific application -- utility, towing, sport or top speed. The transmission is matched to the power and torque curves of the engine, with each gear being specifically matched to the power and torque curves. The multitronic is in constant flux, so the gear ratios change on the fly to respond to the power and torque curves. So, for example, the car will change in response to a hill, but you don't necessarily have to do so. The constantly changing gears has a similar affect as the throttle, and manages the rpm because it manages the load, to which the rpm responds. It creates a very different driving experience.
While the multitronic is capable of constantly updating its gear ratios, it only has three modes: tiptronic, which simulates a manual shift, "drive" and "sport". (Earlier models only had tiptronic and drive.) You can't load multiple maps into the computer. Audi picks the "sport" map and the economy "drive" map. And Audi picks the simulated gear ratios in Tiptronic mode. With the ability to create endless maps, it might feel like a big limitation to only have three.