I need an easy Bluetooth for my car

Eonon P04pro head unit with DAB adaptor.

Has been wired in to the connects 2 loom adaptor so it drives the Bose amp and speakers.
Yes it goes off with the ignition.

With many Chinese units - you can set how long the unit stays in standby ( for much faster boot up )
I have mine set at 2 days ( the car usually gets used every other day )

If the unit comes out of standby - it takes a bit longer to boot up next time you start the car.

Never had any issue with the battery going flat ( even after a couple of weeks of no use )