The ETA that gets displayed when flying around in supercruise is nice but not really very accurate. It seems to be based on your current speed, but given that you almost never sit at the same speed it tends to read a huge number of days which quickly drops to about 6 seconds and then stays there for the next 30... Wouldn't it be possible to change this to be based on your current acceleration, rather than current speed? Obviously it's never going to be a perfect figure but given that the periods of acceleration/deceleration are a bit more consistent it should at least give a better idea of how long a trip is going to take, especially for the longer distance trips.