The L5 roadmap article mentioned better support for cars but didn’t get very specific.
It looks like MPRIS for better media streaming is in the works. I can stream to my wife’s car via BT but there are issues (changing volume pauses Lollypop, for example).
I’m really hopeful that call support is there too though. Not just for my car, but I’d love to be able to use my BT headphones to make calls. Currently I can only hear through it, it doesn’t show up as an Input Device.
As far as mounting the phone, I have been keeping my eye open for anything that will hold it by magnet the same way as the Lapdock kit. I am sure such a product exists, I just haven’t been looking that hard yet.
For now, my L5 chills out in the cupholder.