They emit water vapor, not liquid water. Gasoline-fueled cars emit roughly the same amount of water as a hydrogen-powered vehicle, so we already know this isn't an issue.

It’s an issue here in Minnesota; intersections and highways where there’s standing traffic are slick from the freezing exhaust condensate, but, to clarify your statement: it potentially wouldn’t be a bigger issue than it already is.

> They emit water vapor, not liquid water

If cold enough, doesn't that just freeze and fall to the ground anyways? Considering some places have between like -30/-20C in the winters.

> But where I live, winters could be a big issue. These vehicles could coat the roads with thin black ice.

I never even considered this as a problem. Is the exhaust liquid water though? Because my understanding of the process is such that is still creates an appreciable amount of heat, causing the exhaust to leave as a vapour (much in the same way water vapour is already expelled from catalyzed ICE exhaust, or people breathing).

I've seen a Mirai release a small amount of liquid water before. It could indeed be an issue.

Have you ever looked at tail pipe of car in freezing weather? Most of that is water vapor. Some fraction is particulate emissions, but most of it is vapor. Mostly don't see this in summer. But cars have been for century produced water as exhaust with no issues. Water from hydrogen is really not that different.

Gas already has lots of hydrogen atoms attached to the carbon chains that in part burn to water. Diesel a slightly lower ratio since it is longer chain but still puts out a lot of water vapor. Why would this make a difference?