Being old school and ever the optimist, I say bin them all and go back to good old rear motor cars
Cars would be on a more level par, much more fun and you only need one variation to race. Also only having one 2wd car to maintain, would allow more people to do a second class like 4wd, which is very under subscribed these days.
As a side note, if people feel they need to have three different 2wd cars, then this could push people away from the class and they concentrate on 4wd anyhow. Two wheel drive won't stay the favoured class forever.