PI475 muscle car is faster than PI 520 street car, is that normal?

[URBirdman]

I was playing single player free play mode. I tried racing a normal circuit track which has many slow sharp corners. I tried driving several different cars and found that a class C PI475 Mustang actually gave faster lap time than a class B PI 520 BRZ, which is very weird - I would expect street cars perform better with corners, plus the BRZ has higher PI than the Mustang…

Is that normally what you see? or maybe the game is just unrealistic?

[GTRC_Devil]

It’s not uncommon. The PI system isn’t a very reliable indicator of performance relative to other cars to start with. But also, it depends on where the performance is. A lower PI low top end car with better handling, may very well beat a higher PI high top end car with inferior handling at a slow, tight track.

To be more specific, I’d need to know the numbers and track.

[ManteoMax]

One track isn’t sufficient comparison.

@JONK1969

Forza uses a classification and “Performance Index” scoring system to fairly balance cars across the game. This PI system refers to a ranking number based on a car’s best lap time around a simulated test track. The slower the lap time, the lower the PI number; the faster the lap time the higher the PI. This test track is mathematically generated to be representative of all the race tracks in a specific game. We call this a “PI test track.”

PI ranking, however, is different for each game. It is relative to each game’s car list and race routes. Each new Forza title gets another revision of this test track to be a good representational average of all tracks in the game.

…

We rarely hand tune PI, and if so it is to maintain fair game balance across career, multiplayer, and leaderboards, or to keep cars of similar type and performance in the real world in similar PI ranges or classes, and never to a degree that a car’s performance characteristics are significantly compromised compared to its real world counterpart.

[Swerve_C10]

@URBirdman

I was playing single player free play mode. I tried racing a normal circuit track which has many slow sharp corners. I tried driving several different cars and found that a class C PI475 Mustang actually gave faster lap time than a class B PI 520 BRZ, which is very weird - I would expect street cars perform better with corners, plus the BRZ has higher PI than the Mustang…

Is that normally what you see? or maybe the game is just unrealistic?

Depends on track. If you’re driving the cars at road America or Sebring I would expect the mustang to be faster because both of those tracks have multiple very long straights where acceleration and top speed matter more than grio.

If you’re at a more technical track like Cataluna, the BRZ should be faster as long as you’re not braking too much. In addition the BRZ has really good top end but it takes a bit to tap into that speed. This car should torch the Mustang at momentum tracks at Dubai, Prague and bernese alps.