Cool I thought the same haha
Had a look at the app and it is as accurate as it can be, the calc is mathematically correct.It’s accurately off. I use it as a guide and it seems the max speed it about 20% too high. It’s nice to compare setups or when setting up a car what gearing it will take to get it comparable to my other cars,
It just can’t factor in all the variables that affect the actual real speed of the car, which there are many of.
Like wind resistance, driveline losses, battery sag, rolling resistance, ballooning of the tires, efficiency of the motor and esc etc.
That’s gonna be the same for any speed/rc gear calculator, they all use the same math.