I was thinking something similar. Will there be a weather-proof/resistant model at any time do you think, Steve?
These can get wet without any problem. Not sure what "weather proof" is going to do for you to be honest. I would have no problem using these in a boat so i think your car will be fine.
Um...why would you want a volt meter under your hood? And just for arguments sake if you carefully apply a good coat of conformal coating or liquid electrical tape on the meter and seal it all in good it will be water proof. Hell...buy one have it shipped to me and I'll do it for you. I've been doing it for years with $300 rc car speed controllers with a 0 fail rate.
Edit, I think I quoted the wrong person, this is for Gunnem