That depends on what you consider a benefit.
Does it make the cooling system more efficient? Sure. But the system is plenty efficient already.
Water wetter has some possibly ugly side effects as well - it drops the surface tension on water by a lot. What does this mean? It means that small leaks become big leaks, and areas that don't leak at all without it may very well leak with it. If you have some WW handy, try this: Fill a tupperware container halfway full of water, seal it, and shake it. Leaks? None. Open it back up and put a capful of WW in it, seal it, and shake again. I advise doing it over the sink, though, or have a towel handy!
Bottom line: I wouldn't put it into a car unless I was 110% confident of the cooling system integrity.