My phone wouldn't have lasted the 4-5 hours that call lasted without being connected to the USB port at the same time, I fear. :)
Then again, the companies probably don't want to put out such flexible devices; they want you to pay for it in the form of extra adapters and such.
Or substitute ANY popular mobile game, because gaming essentially guzzles your battery, and you don't want your fellow subway riders have to listen to your game. (People actually have gotten violent towards offenders)
If it were just music it would be ok, but once you want the screen showing a map all the time you're going to run out of juice really fast.
It's not everyday, but it's still going to be annoying the times where it does come into play.
Solution: buy a new car.
Bluetooth audio can be lossy and poor.
The default minimum standard SBC codec is pretty terrible, no doubt, but every device worth using supports many other codecs which are sufficiently high quality for car use. AAC and MP3 are commonly supported, which also happen to be the formats your audio probably is already in. A player focused on quality could, in theory, pass the raw input data over the Bluetooth link for it to be decoded on the car/headphone side. In that case there would be no quality loss, though you'd lose the ability to mix in other audio such as notifications, so I doubt this mode is used by default on smartphones. Dedicated music players may support it.
Since there's arbitrary codec support technically with support from both sides you could also send a lossless stream up to the bandwidth limits. I don't believe there's widespread support for any lossless codecs, but the technology definitely allows it.
Even if you're just using one of the high-quality lossy codecs like aptX you still have to keep in mind the environment. Unless you have an uber-luxury car the noises of normal driving will have more of an effect on the audio quality than the Bluetooth stream. Sure, you might be able to tell the difference when parked, but unless you spend a lot of time sitting around waiting in your car that's not very relevant.
My phone already indexes all of my podcasts and audiobooks, why wouldn't I want it to play them everywhere?
Wouldn't the better solution be to have wireless headphones so you are tethered to the chair while your phone is charging?