Subwoofer Voice Coils

What is the benefit of using a dual voice coil sub vs. a single voice coil sub? I understand quite a bit about car audio, but never really got a good explanation on the subs voice coils.

Thanks.

the benefit is different wiring configurations.

A dual 4 ohm woofer is able to be easily wired to 2 or 8 ohm or you can use one coil for a 4 ohm load.

If you want to use one coil it also has some benefits. You can adjust the qts of the subwoofer by using one as an eletromagnetic brake by keeping the coil open, short or using a resistor. The benefit is that you can tweak it to work better in a wider variety of boxes, but the drawback is that you lose 3 DB of efficiency and putting power to one coil the thermal power handling is about 2/3 what using both coils would be.