Too many deficits

This heater should ensure in an e-vehicle fogging and ice-free windows.
Unfortunately, it does not meet the requirements.
Even after prolonged operating time (about 25 minutes) is only a mild heat from the "heater".
The fact is that the cable to the heater warms up (!), Which represents a safety risk in my view.

Overnight Preheat is likely to be, after about three hours should not start an average car.

For the disc is a complete plan, not domed, disc required, which is the case in very few vehicles. In a VW Beetle, the suction cups can not be used for example.
Here the lead is too short to extend to the cigarette lighter.

If you still want to take this folding window heater should replace at least the lead, against a significantly larger cross-section, extend this if necessary and optimally would be a switchable 12V plug with light, so you can see better if the heater is on.
However, this alone exceeds the replacement value of the heater.

During the ride clatters and rattles the heating annoying.

I would recommend this heater under any circumstances.