We have solved the problem of the ever-growing bonuses with this years rule modifications.
However, a new problem appeared. Take a look at the amount of negative bonuses (which is always the same as the sum of the positive) allocated this year:
ZCT92: -24
ZCT93: -26
ZCT94: -35
ZCT95: -37
ZCT96: -40
ZCT97: -45
ZCT98: -55
ZCT99: -60
The value is growing quite fast, which results in the polarization of the bonuses - some go skyhigh, while others are way under 0. Imagine if the podiumers would have all used the jaguar on ZCT98, now its "bonus" would be -39.
The reason for this is the system which raises the positive bonus by one each month, when the car was not used (for example the carrera currently got +8).
I do not want to interfere with this in this season, but this problem needs to be sorted out for 2010, else this will result in an automatic rotation of the car of the month, without the possibility for battle between cars. As some bonsues go way under zero, these cars are not used for long times. The bonuses keep growing and growing, thus further speeding this process, resulting in ever-bigger bonuses.
I see two possible ways to solve this problem:
1. Defining a peak value for the positive bonus. I would suggest +4 or +5. This would perhaps also solve another weak point in the system: kicking out popular cars for longer periods from being competitive, as some pipsqueaks not heading for the podium use it regularly, dropping its bonus. (the same reason why the only top 12 counts for the bonus changes rule was introduced)
With the current rules, if ZCT99 will be a full-ferrari race, the amount for ZCT100 will be -67
With the +4 peak, if ZCT99 will be a full-ferrari race, this amount would be: -47. The theoretical maximum with this recommendation (every car gets +4 except the one used by all the pipsqueaks) : 13x4=52. We are quite close to it

2. Furthermore, it might would be wise to start the bonuses for unused cars from +1 instead of +2. This would slow down the rotation a bit.
Your opinion and suggestions are welcome.
What do you think? Is this a good solution? Or is the problem even bigger than we think and we should react now, and not wait for the next season?