In my opinion they really should just make the SG vlocities into 5 car sets. Unlike the BG lines, SG has more infrastructure for 5 car length, which is very convenient. It means that a first class carriage could be installed (I personally don’t think it would be required though).
Importantly it means services can run as a single 5 car set so that the same buffet can always be open, but also allows more maintenance flexibility or increased services.
This has been discussed ad infinitum on RP - where is the maintenance to be done on these SG sets and what is the capacity of said depots?
As one RP poster has been saying for years 4 or 5 car sets on the BG could give much more operational flexibility but V/Line seem to be sticking to their guns and keeping everything to 3 cars.
Possibly because they don't want to spend the $$$ on enlarging the maintenance depots just for a few trains a week when the 3 / 6 works fine for many existing services (don't get me wrong, my opinion is that it is just V/Line being lazy but at the end of the day the government just seems to do what V/Line say no matter how foolish or inefficient it appears to others)