I used to do okay with Invisible Glass. I'm now a Sprayway fan just because of price and Wal-Mart availability. Works very well and it's the cheapest? The search is over!
However, here's my glass cleaning protocol, which I learned from me mum: do it twice. Clean the glass (she used Windex) with paper towels, do the best you can, then do it all over again. (And for inside windshield film, I've learned that two, three, many passes might be required, also, park it pointed at the sunset.)
Normally on a dirty windshield, I do the first pass with Windex or the Wal-Mart version of blue Windexy cleaner, second pass, Sprayway cleaner, starting with regular paper towel, final buff with Scott paper towel for glass & chrome.
But back when I was on the road every spring and summer, in my friend's van towing his race car, I don't know if I used the Stoner Invisbile Glass twice. I'm sure I made it cleaner than it had been since the last gas stop, of course.
Let me know how that wand works out! Just got a new used Ford Transit and might need one.