Using my own formula, here's my calculated or projected top speed of the fastest car, Koenigsegg Jesko Absolut, based on these parameters and conditions. Not knowing the actual powertrain loss, I can only work in reverse, like reverse engineering it, tie and match the horsepower loss to the other parameters. Solving S directly is not possible since it's not possible to isolate S or speed in the equation. One work around is to rearrange the formula and iterate to solve for S.
Air density or rho = 1.225 kg/m^3; 0.076474 lb/ft^3; 0.0023769 slug/ft^3 -> 59 F; 29.92 inHg; dry air or 0% humidity
S = Top speed (calculated) in mph
H = Horsepower (crank or Bhp)
Wt = Weight (Total) of car, driver and downforce, if any, in lbs (Wc + Wd + Df)
Wc = Weight of car in lbs
Wd = Weight of driver in lbs
Df = Downforce in lbs
Pl = Powertrain loss in decimal form -> 09% = 0.09; 10% = 0.10; 11% = 0.11; 12% = 0.12
Af = Frontal area in sq ft
Cd = Coefficient of drag
Cr = Coefficient of rolling resistance
H = [0.0025565AfCdS^3 + CrS(Wc + Wd + Df)]/[375(1 - pl)]
H = 1,600
S = 331.65 @9% Pl; 330.40 @10% Pl; 329.14 @11% Pl; 327,87 @12% Pl
Wt = 3,561 -> Wc = 3,065; Wd = 165; Df = 331
Pl = 9%, 10%, 11%, 12%
Af = 20.24 sq ft
Cd = 0.278
Cr = 0.018
