Around 40F today. Is it too cold, i.e. am I wasting good product? I only have one coat on it, and I have a feeling it's going to be a bad winter in the NY area.

 

nope. knock yourself out. just won't dry as fast even if you use ZFX with Z2 or Z5.

 

Below 30 here in Boston (actually below 20 now, but 9pm).
After pressure washing the recent snow/sand/salt/etc crud off the car, I have a nice protective ice sheet over much of it
No Zaino here ...

 

below 50 F, will take a verrrrry loooooong time to dry, even with the ZFX.

 

When applying Zaino in cold weather (say below 50F), the ZFX helps the polish to dry relatively quickly unless it's very cold and then I would recommend leaving it overnight or alternately several hours during the day. It will generally be dry and ready to buff (chalk-like and no smears) when you get up in the morning. If you don't have ZFX it will definitely take a longgggggg time to dry.