I think the car bonus system is something amazing that ZakStunts has and indeed, I've seen almost every car used in races, so it works very well. There is only one goal that seems very hard to achieve: car diversity on the same race. It looks like, while cars from race to race change a lot, the trend is to use only one car or two per race. I can think of a few ideas that could help in this regard, but all of them are risky, that is, they could lead to undesired, unexpected results as well.
For example, what if, like in the currency market, cars coeficients would float during the race? Say, using a car that hasn't been used on the race when at least other two different cars have been used already will signify an extra little bonus to the first pipsqueak using it. I know, very complicated, but this idea could lead to something simpler if analysed. Also, what if a pipsqueak would get a lower bonus on a car if he used the same car on the previous race, but pipsqueaks who didn't will get the normal bonus?
Another idea, longer to apply, but simpler. Suppose initial bonuses are assigned to cars from simple tests on tracks for the first race and then, on every next race, instead of trying to make the cars cycle, bonuses are recalculated according the the diversity obtained on the previous race and seeking a greater diversity? The problem with this is that a whole season of racing would be sacrificed for this calculation. But, I could use R4K for this purpose next year... I don't know.
Now, beside any of these crazy ideas that are just brainstorming (feel free to use your creativity on them and change them wildly, ha, ha), one thing I'd like to propose is a field in ZakStunts where one can enter a lap and a car and obtain the lap with bonus applied or maybe like this: you click on one result on the scoreboard and that can take you to a menu where you can select one of the available cars and ZakStunts will calculate what lap you need to reach that pipsqueak with the car you selected. That tool would make it a lot more comfortable for pipsqueaks and would make them more eager to pick different cars instead of following the one that everybody's using. What do you think?