I've seen a similar thread with my issue but since it's now closed, I would like to post similar BT issue of mine to this thread.

I am using my Ubuntu Touch on Nexus 5 and connected to my 2016 Subaru and here are my issues

0. Turn on BT radio on my Nexus 5
1. Ignition. Nexus 5 reboots immediately after being recognized by Subaru.
2. Podcast streams no problem via Car stereo once rebooted.
3. After returning to my car, both N5 and Subaru recognizes and confirms re-connection via respectful menus
4. Once Podcast resumed, audio is coming out of N5 only. Car stereos r dead silent.
5. reset BT radio on N5 and loops back to 1)

Sidenote:
mobile battery indicator on my Subaru shows 0%; even for a fully charged N5 running Ubuntu Touch. Indicator performs correctly when iPhone or other Android phones r connected to vehicle.

I don't take calls while I drive so I haven't been able to test any telephone related with BT. Sorry about that but I hope my input could provide some help solving BT problem in general.

I'm guessing it won't b much of an help, but...

In my case, I installed UT on a Nexus 5 fresh out of a sealed box; using Manjaro Linux. I didn't even check the version but the installation went smoothly.

@ernest Thank you very much. Will do.

I've switched over to Ubuntu Touch recently and have Ubuntu Touch 16.04 Stable on Nexus 5.

So far I love using it as my daily driver, but whenever I have to use a calculator, I find myself pulling out my old(?) iPhone. The only reason is because the Calculator on UT has no [-/+] button to flip the final value.

I assumed it gets utilized quite a lot in general, and was surprised to see its omission on the Calculator. I often calculate series of usages in % and the fact that I have to run back for my old phone or an actual calculator during workflow is a bit disappointing.

Hope the team will look into this.

Cheers,
B