To prove if they work you would really need laboratory conditions , there may be a placebo effect going on and if they do work you don't want to drive a vw thas running below optimum temp ,I can understand an early with smaller vents running a big engine maybe seeing a benefit but not a standard engine .....maybe but your fan will only shift a set amount of air unless your running a bigger fan
Teachers aren't necessarily the most knowledgeable on a particular subject....but they do know how to put it across....I think you have the just right outlook to moderate on here
You polish your car before you wash it?!? How odd I was in Asda once and the there was a woman by the Polish section looking for Mr Sheen. She stopped a shelf stacker (who happened to be English!?!) to ask for help and we both *******ed ourselves laughing