This function is practical for those who forget to save the game but, honestly, I think it's a bad idea. According the game is explored and there is more data to save, it becomes annoying! Especially in multiplayer for the host which is overloaded with save game request whenever a friend uses a vehicle the host is harmed with frequent lags. You need to deactivate this or, via menu option to deactivate this function, as in skyrim you can deactivate save when traveling. I know this will be resolved with the dedicated server but until then it would be interesting to disable save on vehicle seat.
I talked to some friends about this and I add that everyone agreed that this is a big problem in multiplayer game. Therefore, I am here representing the opinion and request of many players from my country (Brazil).
Sorry for my bad english!