I have to disagree about BT 5.0, I dont think for a product I side your car will make any difference.
1.) Bt 5.0 touts extended range which is moot for a device that remains inside your car and will only ever be connected when your phone is in the car.
2.) Bluetooth 5 doubles the bandwidth by doubling the speed of transmission, which in a car with a device within its confines space would be fractions of a millisecond that your ears and brain cannot discern from 4.2's transmission
3.) Low power consunption... also a moot point since this device draws its power directly from the car. Your phone will generally be powered up while in the car as well.
UGH tere is no added benefit of having BT 5.0 with this device, it's just an added cost that's unnecessary