Increase the scope of the editor. How about car colours and designs? Save custom edits? Driver skill? Historical seasons?
You could create the 1975 driver lineup for example, with the option to change the team names, car style (generic 50's, 60's, 70's etc would do), car ability, driver names and abilities, car colours and points system. Maybe add historical circuits and be able to choose a custom calendar. Then save into a custom season slot and be able to upload and share custom seasons with others, a la games like Grand Prix Manager 2 which is still going strong after nearly 20 years.
Witchsmeller Pursuivant commented
It would be fun to recreate classic eras, like the mid 70's or late 80's, I appreciate it's more complicated that just driver names and car colours though, with rules, qualifying, tyre and fuel use, car reliability, calendars, maybe even danger changing vastly over the decades. If it would be possible, I like the idea of having season settings with the chance to change rules on and off, tweak car reliability levels, grid size, season length and circuits included if possible. Big ideas!
Another good idea and something that I've been thinking about - classic racing.