Great idea and demo. My main gripe when using Google Maps in the car is lack of information about the next turns — when do I change lanes, and to which one? This could be natively addressed here, especially if the blue navigation line was a little thinner and showed which lane(s) the driver needs to take.
This comment confuses me a bit because Google Maps (at least in the US, in my experience) is really great about telling you what lane to be in.