coats that look white when in car headlights?

Not sure what your use-case is but if you want to add reflectivity to clothes when you need it but look normal the rest of the time then I dont think you can beat –

Folds up small enough to fit in a jacket pocket, fits over pretty much anything so you can wear it over a t-shirt or a thick winter coat.  I tend to stick it on when I’m wearing dark clothes at night in winter on a brompton.

I thought the spray-on stuff sounded great but then read this:

The spray lasts for approximately a week after application, depending on the texture of the surface you spray

Basically useless unless you were doing some temporary signs or something.

I have a proviz 360 for commuting now the nights have drawn in – it is hot and sweaty no doubt, but I wouldn’t change it for anything less visible on the road, it gives me so much confidence that I have been seen and makes me feel a lot safer

The gilet probably would have been a better bet in truth as a bit cooler, but happy as is.

I wouldn’t wear it for a daylight long ride unless it was super cold out, but if its dark on the road then I don’t think twice about it.

I’m using an Altura NV. Doesn’t get too hot, pretty breathable, has reflective sections and is a bright green for daylight