How to set Bluetooth priority to car, not hearing aids, for incoming phone calls

My iPhone is paired to both my hearing aids (via Accessibiltiy/MFi) and my Mazda (via regular Bluetooth). I can initiate a phone call from the car, but incoming calls go directly to my hearing aids, meaning I need to use the iPhone to answer the call and use the mic on the phone to speak. There's a setting under

Accessibility / Hearing Devices / Audio Routing / Call Audio that I could change from Automatic to Never Hearing Devices each time I get into the car (and then reset back to Automatic when I leave the car), but I'm wondering if there's any way around this.