With the iRacing Race Participation Credit Program, it is important to note that the Race Participation Credits are awarded per series, so for multiclass series you cannot double-up on your Participation Credits by running both classes of cars, but you can get series credits if you alternate between the two. For example, if you run 3 weeks in one class, and then complete 5 other weeks in the other class, that would constitute 8 weeks of participation in the series, and you would qualify for iRacing Race Participation Credits for that series.
For shorter series that don't feature a 12-week schedule, the required number of weeks will be determined by the number of "drop" weeks for the series. For example, an 8-week series with 2 "drop" weeks would require 6 weeks of participation. This means that IndyCar Series -- which is divided into the 6-week Indy Road series and the 6-week Indy Oval series -- is still a part of the Race Participation Credit Program. While a normal 12-week series would require 8 out of 12 weeks, the Indy Road series will only require 4 out of 6 weeks to qualify for Race Participation Credits, and the Indy Oval series will also only require 4 out of 6 weeks of participation.
For shorter series that don't feature a 12-week schedule, the required number of weeks will be determined by the number of "drop" weeks for the series. For example, an 8-week series with 2 "drop" weeks would require 6 weeks of participation. This means that IndyCar Series -- which is divided into the 6-week Indy Road series and the 6-week Indy Oval series -- is still a part of the Race Participation Credit Program. While a normal 12-week series would require 8 out of 12 weeks, the Indy Road series will only require 4 out of 6 weeks to qualify for Race Participation Credits, and the Indy Oval series will also only require 4 out of 6 weeks of participation.