It is all or nothing in this case. You disconnect your car antenna just so you can connect it to a second antenna in your phone. You do end up getting nothing.

Hooking your phone up to your car is one of the worse things you can possibly do privacy-wise. If you're going to do that, you can save yourself the trouble and keep the car's internet, GPS, microphone and camera turned on.

but will take the microphone with it

But that's a good thing, no? Is there any good reason to use the car's mic?

It's been unmaintained for years. The developer moved on to uBlock Origin. You should too.