This is my method for cleaning the car windows, mirrors and headlamps.
I've cleaned the glass in this way for at least 20 years with no issues and its fast for a very good result. Based on a 4 door saloon/sedan.


Equipment:
1. A pump action bottle of Fast Glass.
2. A new roll of paper kitchen towels. In the UK its just called "kitchen roll"
3. A plastic carrier bag for the used kitchen roll.

In a rush I can clean the external window glass and the mirrors to a high standard in about 5 minutes. For a top job the external glass would take me 10 to 15 minutes.

One panel of glass at a time, spray about 4 or 5 blobs of Fast Glass evenly on each side windows and then use the kitchen roll to clean the glass. For the front and rear screens I do them half at a time standing each side of the car with 5 or 6 blobs Fast Glass evenly over each half. I move the kitchen roll quickly because the Fast Glass seems to evaporate fairly quickly on warm days. I tear off 2 or 3 sheets for each use and use maybe 6 to 8 sheets per pane of glass. I tend to go round the car clockwise or anti-clockwise and do them all.

You do have to be careful how you spray it, because it runs and any overspray on paint or rubber has to be wiped off because it looks unsightly. But with practise you can work out how much to spray and how hard to pump for any situation. You still have to watch out for grit so as not to scratch the glass same as any cloth or wipes. If the windows are heavily soiled I do a quick spray and gentle wipe over first to remove heavy dirt and grit before doing a proper clean.

The inside glass takes much longer because of the need to clean it more thoroughly and to make sure I don't get spray everywhere.

But for a fast clean when I'm going out it takes 5 or 6 minutes to do all the external window glass and mirror glass.
The carrier bag is to put the used kicthen roll in as you go round the car. Its not nice and it needs to go straight in the garbage bin and not in the boot ! Fast Glass does have quite a strong solvent smell to it if anyone suffers from reaction to those things.

Anyway... its quick and easy even when you want a top job.
The Fast Glass and a roll or two of kitchen roll are always kept in the boot tidy.