How far away do you need to start your car? Wouldn't a regular remote start on a key fob work for most situations? Unless you're taking the bus to your car.
The only reason I didn't buy one is because of its bezels which got bigger than last year. I want to support smaller phones but they make it really hard.
I would use Photoshop or Gimp to make the custom resolution and position and then stretch the highest resolution wallpaper over it. You can always go with two portals if matching doesn't work.
You can already do that with Chromecast for example. Just press cast to TV and resume where you left off. It uses the device wifi to stream it instead of your phone.
How far away do you need to start your car? Wouldn't a regular remote start on a key fob work for most situations? Unless you're taking the bus to your car.