I would like to see some sort of radar system that shows other cars relative position on the track (along with the track boundary) within a couple of car lengths of your car. I think it would make sim racing a bit cleaner as you could then easily glance at the radar map when approching a corner/bend to see if anyone is sneaking up on your inside or outside, and adjust your line appropriately. At the moment we have mirrors to check and can turn left or right but it is nowhere near as good as using peripheral vision when driving a real car, so I think it would be a very worthwhile addition.