I'm using this in my Audi A6 and the 12 Volt socket is by the armrest, so depending how you plug it in you may not be able to see the blue light on the charger so you can't tell when it's switched on or off. You could just leave it pushed in and switched on permanently but there may be very minimal battery drain. I've left it plugged in many a time and it hasn't drained any battery current that made a difference.
The coiled usb-type C lead is at full stretch if I try to charge my phone when it's in my dashboard mounted phone holder and it's not practical as it blocks the gear lever. So I use the usb-type A port with a longer lead.
The usb-c would be fine for a passenger to charge their phone in my opinion though.
The attached usb-type C cord doesn't charge my particular phone a Samsung S9 Plus in the Fast Charging mode. The usb-type A, port does though.
When in use I haven't had the charger pop out of the 12 Volt socket at all and it's a snug fit.
I can recommend the charger as a good purchase as well as Mobile fun