Forza Motorsport car Performance Index (PI), explained

There are several rating systems that determine a car’s performance in Forza Motorsport, but there is one stat called Performance Index that tries to be the definitive judgment of how good each car in the game is. We will explain what PI is and how it’s used to sort the best from the rest in Forza Motorsport.

What is PI in Forza Motorsport?

There are four main performance categories by which Forza Motorsport cars are measured—speed, acceleration, handling, and braking. These give a good indication of how good a car is in different performance aspects. PI, which stands for Performance Index, tries to mesh all of these in one stat that can tell you straight away what sort of performance you can expect from a certain vehicle.

How is a car’s PI determined in Forza Motorsport?

PI is calculated in the most sim-racing video game way possible—by simulating a race. A car’s PI is determined by its performance on a virtual test track, designed to be an average representation of all tracks included in Forza Motorsport. The longer it takes the car to complete a lap on the virtual track, the lower its PI.

While the idea behind the Performance Index is noble, it has one obvious flaw. An average assessment doesn’t mean all that much in a game with varying tracks. A car with a lower PI can be better than another with a higher PI on certain tracks and in certain conditions. Turn 10 acknowledges this and outlines that PI can be used for gathering a general idea of how a car will perform in Forza Motorsport, but it doesn’t guarantee that level of performance all of the time on all of the tracks.

What is PI used for in Forza Motorsport?

PI determines a car’s class in Forza Motorsport. There are nine total classes, divided by their PI, which can be anywhere between 0 and 999. Here are all the classes in Forza Motorsport and their PI regulations:

• Class X – 999 PI
• Class P – 901-998 PI
• Class R – 801-900 PI
• Class S – 701-800 PI
• Class A – 601-700 PI
• Class B – 501-600 PI
• Class C – 401-500 PI
• Class D – 301-400 PI
• Class E – 0-300 PI

Can you boost a car’s PI in Forza Motorsport?

Yes, boosting a car’s PI is possible by upgrading it. Upgrades are unique for each car and can be applied by spending Car Points. There are restrictions in place in some instances, where you can’t increase a car’s Performance Index beyond a certain threshold, at which point you won’t be allowed to spend any more CP on that car.