With Ethernet, a standard that has been used successfully for years now in networking is currently being introduced to automotive electronics. In addition to inexpensive components, a major advantage is the extremely high bandwidth - in onboard communication as well as in diagnostics and flash programming.
The bus physics will differ for the two application cases; in diagnostics / flash programming, it corresponds to the familiar standard.
Softing has been using the standard for quite some time for linking interfaces to the PC. This is why the company collaborated on the standardization of diagnostic issues (in the DoIP protocol) from the outset.