Re: Google maps does all this already...
It'll be a long while before built in is actually in most cars - is it even in "most cars sold today"?
I genuinely don't know the answer to that - it wouldn't be on my list of things to look for (whereas a decent shelf for a tablet would be - unless of course someone gets me a Tesla Model S, in which case I'll use that fantastic screen)
Cars live for a long while on the roads - the *average* age of a car on the road is 11-12 years in the US, and 8 in the UK.
For that to be the average, given the stability of the total numbers (both the average age and total number are creeping upwards, but relatively slowly) cars must leave the road at an average age of 16 years.
To get "most" cars to have any technology takes a reasonably long time.
The biggest benefit of the in car system is the availability of power, the biggest issue is the usual lack of updates (here things like the Tesla win hands down - I don't know how many other manufacturers do the same?)