[paul.fr]

If the majority of carswere powered by hydrogen, their exhaust emissions would be water. Would this lead to wetter roads? and possibly more accidents due to wet road conditions?

[another_someone]

I doubt you would get liquid water on the roads, but you could get more mist and fog.  I would expect that you are likely to have the water leaving the exhaust at too high a temperature to condense into water immediately upon leaving the exhaust.

[daveshorts]

Yes you would need to burn an immense amount of hydrogen to compare to the amount of water put into the air on a warm day by evaporation.

[lyner]

Why are people so chuffed with hydrogen powered transport?
Hydrogen is not an 'energy resource'; you can't find it anywhere except chemically combined with something else ( as water, for instance).
You still have to make it using some other energy source. The only good thing about hydrogen (and it IS a good thing) is that it produces very low LOCAL pollution. Someone else, somewhere else, already produced the bad pollution..
There's nothing for it but to walk everywhere, folks.

[_Stefan_]

There are cars that run on compressed air and don't 'burn' anything at all