This is a personal project which I’m starting afresh for the new Motorsport.
The table above will help me calculate a new PI-rating for every in-game vehicle based on lap performance.
As a quick rundown, here’s what the table records (L to R):
- Columns 1-7 record information about the vehicle.
- Column 8 records the vehicles best lap time.
- Columns 9-10 calculate the split between each vehicle and the benchmark.
- Column 11 calculates the Performance Split Ratio for the vehicle.
- Column 12 divides the lap time split by the average PSR for all vehicles.
- Columns 13-14 calculate a new PI-rating and how it compares to the existing.
In previous Forza titles there have always been vehicles which over and under perform relative to the PI-rating. I enjoy discovering these vehicles, watching how performance varies depending on track layout, and discovering which track(s) most closely align with the official Performance Index test circuit.
For anyone who may wish to follow along, I’ll update my progress as I complete each section. At present, I’m working through E-class on Spa Francorchamps.
Leaderboard:
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Cool, can’t wait to see some data out of this!
Still working through D-class on Spa Francorchamps. Will hopefully have the results up at some point over the weekend.
In the meantime, here’s a short video comparing an in-game lap to a real-life lap.
Same car. Same track. Same driver. 
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I am also noticing a few trends - some good, some not.
The good:
For me, AWD vehicles feel more fun. In standard form, some of them still feel a bit breathless (e.g. the Mitsubishi Evo 8 / 9 / 10 models) but others are better and rotation on corner entry feels less wooden and more natural. I like this.
The not so good:
Speaking of corner entry, I’ve noticed three strange and frustrating behaviours.
The first concerns braking - on some cars the brakes feel broken. Simple as. I can apply the brakes in a nice straight line on a perfectly flat section of track and the vehicle will start veering left and right. I’m testing every car in standard form so there’s no tune messing with the settings here.
The second behaviour concerns downshifting. I have found the most consistent and effective way to downshift in this Forza is to pull the paddle just as I am hitting the brakes. If I do the opposite and hit the brakes first, I’ve noticed that I sometimes lose braking performance - as if the brief blip of the throttle during the downshift is somehow over-riding my braking input.
Finally, the third unfortunate trend is the rear wheel squeal / skid in quite a few FWD (and one or two AWD) vehicles. I’m currently testing on Circuit De Spa Francorchamps and the issue is really apparent through T11 and T12 (although it can also occur through T13 and T14). While FWD vehicles can often lift or lock-up the inside rear wheel, this behaviour goes beyond that and feels… not quite right. Everything from how the behaviour initiates to how it impacts vehicle dynamics and for how long - even the way it sounds - feels exaggerated.
Verdict:
So to quickly sum this up… I’m landing somewhere between frustrated and disappointed so far. I’ve always loved Forza for its fun and varied car list but so far, because of the issues above, several chunks of that list are in the bin for me with this one.
Let’s hope it’s get better in the remaining classes. 
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Unfortunately, I’m enjoying my play time less and less so I’m calling it here for this one.
Forza for me is all about the cars and I was really excited by the prospect of a new, “built from the ground up” game with accurate vehicle modelling and dynamics with a revised Performance Index system. My interest peaked when Chris Esaki said that every vehicle had been lapped and given a fresh PI rating.
It’s become increasingly clear for me however that this is not the case with the same patterns and trends carrying over from previous titles into the new game. In addition, the dynamics of certain vehicles leaves me wondering whether they were tested at all (and therefore deemed acceptable and representative of what the developers were aiming for) or whether they were simply added and forgotten about.
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