Currently, their vehicles are operating with a system called Tesla Maps. This proposed update will be more than just an improvement on this system, but a complete overhaul. Musk warns his followers that the new system will roll out this weekend not as a finished product, but as a mature beta.
"New nav starts rolling out this weekend. Should be considered a mature beta at first, so won’t be perfect, but will improve rapidly. With the old system, we were stuck with legacy 3rd party black box code and stale data. No way to improve."
The new system will reportedly have a smoother engine and better zooming. It's expected to have an entirely new routing engine, which has been a common complaint in the past.
I make it sound like this is some spontaneous action by Musk, but he's actually had this in the works since last December. He estimated the project's launch as "early 2018." I'd call that an accurate guess.
"Major navigation overhaul coming in early 2018. Will be light-years ahead of current system, but we are testing it rigorously before rolling out."
