While not exactly a hose expert, as the owner of a car wash I'm forced to know something about the stuff. Nothing is as simple as it seems...
The product is properly called tubing, not hose. That being said, the typical tubing used in these applications is clear PVC. One brand name is Tygon. There are various grades of the stuff, but they all
look pretty much the same. They are chemically different. There is high quality tubing,low quality tubing, tubing designed for pressure, those for suction, those for fixed use, and those for flex. Some are for peristaltic pumps. Some can bend, some will kink. However when you go to Home Depot or other stores like them, you simply buy clear PVC tubing. If you want to see a good selection of this kind of tubing (and a whole lot more) take a look here:
http://www.usplastic.com/catalog/category.asp?catalog%5Fname=USPlastic&category%5Fname=18308&Page=1Since wiper fluid isn't exactly a critical item (such as a brake line)don't worry about quality. The cheap stuff will work. It will harden with time, turn yellow, etc. When it does, buy a new piece then, and install it.
Some Tygon tubing I bought recently is free of plasticizers, so it can't get hard in the car wash chemicals. It was something like $2.50 per foot which is somewhat more expensive then the MB stuff.
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored