This app was mentioned in 9 comments, with an average of 2.00 upvotes
I've had luck in the past addressing this with an app called Media Button Router. It can put up a menu of which app you want to play the music in when it gets a Play command over Bluetooth, but this menu can be empty and time out immediately, on which case it won't play anything.
https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr
I'm currently using a Tasker profile to address this.
Hey I hope I'm understanding you correctly. This happened when I got my new Toyota too. A Bluetooth connection automatically opened a music app whether I wanted it or not. I use an app called media button router.
Sorry, I'm in mobile so the link may be messed up.
As far as I've been able to figure out it's the car that's sending a play command to the phone. The media button router app will allow you to set a list of apps you'd like to choose from to autoplay. Or you can make the list empty and then no app will autoplay. That solved my problem.
I had the same issue with all of my phones (HTC EVO 4G, 4G LTE, Moto X, etc.). The way I work around it is by using an App called Media Button Router. This basically intercepts the "play" button press when your car starts up or when a bluetooth audio device connects. It's not a perfect solution, but at least it stops my car from blasting tunes when I don't want it to.
Running a 6p with a Ford fiesta today, but when i had my m8, i was able to do what you're trying to with this : (https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr&hl=en&referrer=utm_source%3Dgoogle%26utm_medium%3Dorganic%26utm_term%3Dmedia+button+router+android&pcampaignid=APPU_1_qDbMWLiWMcGkwgS16IroBw) [Media button router]
This is to do with the way that Android routes play commands (be it voice, a button press or over Bluetooth etc). The only reliable way I've found of combating this is using Media Button Router from the Play Store: https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr&hl=en_GB You can have it setup as default where it asks you each time. Alternatively (like me), you can untick everything but Spotify and it'll route to that each and every time. It's an old app now, but still works on 7.1.1.
This is to do with the way that Android routes play commands (be it voice, a button press or over bluetooth etc).
The only reliable way I've found of combatting this is using Media Button Router from the Play Store: https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr&hl=en_GB
You can have it setup as default where it asks you each time. Alternatively (like me), you can untick everything but Google Play Music and it'll route to that each and every time.
It's an old app now, but still works on 7.1.1.
My best suggestion is an app called media button router. Its available on the play store. Essentially it allows you to select which app to open when you connect through Bluetooth. It has a timeout setting and if you don't choose anything, it won't open any apps.
Here's the link: https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr
Does the app in question have an autoplay setting? What about your car's Bluetooth?
A quick work around is this app
https://play.google.com/store/apps/details?id=com.harleensahni.android.mbr