Went over my black X5 yesterday with it after I washed it in the shade on a cool car . . . Used the McGuires spray to give it a little shine and remove water spots. Then parked it in the sun. The sun quickly showed how bad a job on a black car this stuff does. Used micro fiber clothes and it looked gross revealing white haze, spots, swirls, smudges etc. No matter how much I buffed. I guess you get what you pay for $7.99. Im going to try BLACKFIRE WD Polymer Spray Sealant/detailer.
There was also a good youtube review and comparison of 20 detailing sprays (Blackfire was not reviewed) and the number #1 was Bouncers Done and Dusted something, but only available in England.
https://www.amazon.co.uk/Bouncers-Du.../dp/B00W9O3Q1A
The Blackfire I just bought has great reviews on Amazon:
https://www.amazon.com/Blackfire-Pol...lackfire+spray
This guys goofy, but it seems to be honest comparisons of various quick detailing sprays (2 youtube parts):