Very good if you don't expect miracles.
I use it before the car warms up.
As the cold air clears the windows, it keeps you warm.
Then I close it.
Don't expect to get it and burst from the heat.
It will simply be tolerable until the car gives you warm air.

Only for this use and at this price, get it with closed eyes.
If you want something more, it doesn't do.
You have to look at something else