That mix is likely to "burn" paint...be careful, very careful, with that...I'd recommend no more than 1 oz per gallon of any cleaning brew...or better....
...for those NOT worried about freezing mix...
For the thrifty among us, 1qt of actual autoglass wash ($2-3gal, I like RainX windshield mix) to 1 gallon of water...that $2-3 gallon should now last a couple of months...again, THIS is NOT for winter/sub 32°F/0°C use.