Andy's idea is probably the most fair, the only other way to do it without pairing the drivers is to run a handicap system.
Easy to do, decided pretty much the same as the above idea - the commitee decide on peoples abilities.
You have a 'rating' decided for everyone in each class i.e. 2wd, 4wd, micro etc etc . Then if you are a Craig or Rob for instance, they have to have 2 laps deducted from their final position ( a -2 rating ). Andy or Owen for example, 1 lap deducted ( a -1 rating ). Some like Balders would be scratch ( 0 rating ) and this is the 'datum line'.
A beginner like me would be for example a ' + 2' rating, which means id get 2 laps added onto my final position....
Its easy to do, we've used the same basic system for fun tennis tournaments for donkeys years. It does make the competition far closer in direct fun tournaments.
Before you say it, if someone lower ranked does start winning regulary i.e. improving standard quickly, you simply move them up a rating to compensate. Or if someone is at the back regulary, you move them down a rating.
If you feel lap addition/deduction is not the best way to do it, work out the average lap times for a middle standard driver and/subtract a certain amount of time for each level of ability.
The system is very easy, the hardest part is at the start, working peoples abilities. But tbh, most of us have been around for a while, i would think we have a pretty good idea of how good people are, if they are likely to improve quickly etc etc.
And its always a good idea to keep the total levels of abilities low, otherwise it can get confusing - in this case 5 levels would probably do it : -2, -1, 0, +1, +2.
You can still use these as ratings even if you use the 'time' method over the 'laps' method. And you can add an 'most improved driver' catagory as well if you so desired.