Pros: Lets front passengers set their own temperature
Cons: Increases vehicle price; complicates control interface
Summary: If you're shopping for a car and see the term "dual-zone climate control," it refers to a climate control system with two sets of controls: one for the driver and one for the front passenger.
Some cars offer "tri-zone" or even "quad-zone" climate control. These third and fourth zones are for rear passengers. Tri-zone climate control means second-row passengers share a set of controls. Quad-zone climate control can mean that each side of the second row gets individual climate controls, just like the front -- or, in a 3-row vehicle, it can mean that both the second and third seating rows get their own "single-zone" climate controls.
Most common by far, however, is the dual-zone climate control system. It typically features two temperature controls -- one on each side of the control unit -- so the driver and the passenger can create their own microclimates. Some cars also give the passenger a separate fan control and air-flow selector, whereas others limit the "dual" functionality to just that temperature knob.
Naturally, dual-zone climate control costs more than a traditional manual system, so it will tend to inflate the vehicle price. Also, the sometimes complicated controls can make it hard to switch to "single-zone" mode on demand, which is annoying -- dual zones aren't much good when you're driving alone.
Generally, though, there's a lot to like about these systems.
What it means to you: Dual-zone climate control has traditionally been a luxury feature in the U.S., but it's common in Japan, and more and more cars are using it today. It might be more accessible than you think.