I've been away for a lot of this month and, being the only person working on Oversteer Racing, that's meant that work has been slow.
Having said that I have done a bit of play testing and I discovered that NPC cars were taking on too much fuel at pit stops. This made the cars heavy once they had pitted and they were then slow. For a while I thought that there was an issue with the code that determined what the correct fuel load would be for the car to get to the end of the race.
After some debugging and testing I found that the code to determine the fuel loads was correct. The issue was actually far more simple. There was a bug that meant that NPC cars were not receiving the correct information for the race length at the start of the race. At the pit stop the cars were then fuelling up for the number of laps they were expecting but this wasn't the number of laps remaining in the race. It was a simple fix but a bug that took a little time to track down.
I hope to do some work on handling retirements for NPC cars.