Still looking for evidence of rubber banding or boosting for AI opponents, I ran the Gran Turismo 300 race at Autopolis International yesterday.
I chose the 1 chili variant because I preferred to drive the RWD Silvia over the AWD Impreza. My best laptimes were around a 1:53:x. In practice and qualifying, the best competitor seemed to be De Bruin in the MR 2, who was in the 1:54.x region, although sometimes faster. Still, I finished practice first, qualified first and even managed to stay in front at the start of the race. I then ran my race when I noticed that another competitor, Sasaki in an FTO, came up behind me and slowly gained on me, setting a fastest lap - better than my fastest lap in the whole race - out of nowhere. I still managed to stay in front, but I could only keep him behind me at roughly a 1 second gap. Then, from the second to last lap, he suddenly dropped back further and that was it. Seemed strange to me. Where did he suddenly come from in the race, and if he can drive so fast, why did he never put in these times in practice or qualifying?
So I watched the replay of the race. Afterwards I restarted the whole thing to watch how Sasaki generally performs in practice and qualifying. Here's the thing: the FTO is the only FWD car in this race, all other cars are RWD or 4WD. This means that Sasaki is highly dependent, much more than all the other cars, on the condition and temperature of his front tyres because they are doing all the work, propulsion and steering. Additionally, in terms of PP balancing, GT7 gives FWD cars a "PP bonus" due to their natural disadvantage of doing everything through the front wheels. I regularly run the 700 PP 30 minutes @ Le Mans race and there's a Gr. 4 Suzuki Swift which is always in the top group despite being FWD. The game is designed to give FWD cars a slightly lower PP rating so they can compensate their natural disadvantage in racing due to being FWD by e.g. more horsepower.
So here's what I found out about Sasaki in his Mitsubishi FTO in the Autopolis race: in optimal conditions, he is quite clearly the fastest opponent on the grid, being able to put in low 1:53.x laptimes. His performance however stands and falls with the condition of his front tyres. I monitored tyre temperatures during my race yesterday (I can't see opponents tyre temperatures, just my own) and found that it needs roughly 2 laps (the outlap + 1 extra lap) on this track to get the tyres into optimal working range. This has a quite clear impact on laptimes for the RWD and 4WD cars, but for the FWD Mitsubishi, it decides between life and death because he does everthing through his front tyres. So here's the gist for this race:
- Sasaki in the FTO has the power to put in very fast laptimes, but due to having FWD he can only do this with his tyres in optimal working conditions (temperature and wear).
- Tyre temperature gets ideal around the 3rd lap in this 6 lap race.
- Sasaki drops behind a lot at the start due to FWD grip disadvantage over RWD and 4WD.
- Once going and with his tyres warming up, Sasaki can overtake opponents with his superior straight line speed (the game grants him more horsepower to compensate the FWD disadvantage).
- Once Sasaki has a no more traffic in front of him and has his tyres in the ideal temperature window, he starts to put in these 1:53.x laptimes I'd never seen him do before. This happens around lap 3 in this 6 lap race.
- Around lap 5, his front tyres start to show excessive wear (excessive in respect to non-FWD cars) so he suddenly loses quite some performance. The next fastest opponent, De Bruin, catches up to him and starts to fight him for P2. This fight costs Sasaki more valuable time, so his laptimes suddenly plummet.
So me leading the race, Sasaki suddenly appears behind me in lap 3 and matches/exceeds my laptimes, stays on my tail until lap 5 and then suddenly disappears again. That sure looks like the game boosting him to make the race more exciting for me, but if you look at the evidence, it isn't that.
This just leaves the question: if Sasaki can be so fast, where was he in practice and qualifying? Well, it seems that the AI is not aware of his specific abilities, so he never tries to get in a clean lap (no traffic) with his tyres in ideal working condition. During practice he goes on track, does a few laps, comes back in. By accident he can find himself in a situation with ideal tyres and no traffic, but most often he doesn't. And qualifying (12 minutes) is just too short for him to find this sweet spot. A human driver is aware of this and can put in a good laptime in the right situation, but for the AI, this is just one of the cars. The AI doesn't give the FTO the special strategy it needs to be quick. The 6 lap race on the other hand is long enough so that Sasaki comes into his car's ideal working conditions: warm tyres in lap 3, no traffic in front. In lap 5 his tyres are wearing out, so he drops back.