Just a thought which I'm sure not everybody will be in favour of, but one improvement suggestion would be the use of a rolling start.
On a number of tracks trying to safely get around the first couple of corners is quite a challenge from a mid-grid position. Many people seem to be quite determined at this stage of the race, and with everybody bunched so closely trying to avoid an incident can be somewhat difficult.
A simple rule would be to not allow overtaking on lap 1. It would be easy to administer, as the stats will show the order at the end of the lap. Additional rules would be needed to cater for people who spin or cause a crash on that first lap, but that shouldn't occur often given the calibre of drivers we have in the league
On the plus side, as we see in F1 following a few laps with a pace car, the cars will be strung out a bit at the start of the second lap, but with suitable skill a driver can position themselves to make up a place or two with good judgement on the approach to the start line.
I'm sure some people will not like the suggestion, as it is not used in the racing that most of us watch (except Nascar and Indy? (it's not called Indy anymore is it
)), but might be worthy of consideration.