Calculating Top Speed

Wondering how much power it will take to get your car up to 200 MPH? Here’s an equation to help you find out. (this information is from August 2001 Sport Compact Car)

Aero Horsepower: Drag x Speed or HP at the wheels

Frontal Area: Amount of Frontal Area (large hood scoops, mirrors and bumper openings add to this and decrease your top speed.

Cd: Coefficient Drag.

Speed: In MPH

Aero Horsepower (wheel horsepower) = 0.000007 x Frontal Area x Cd x Speed3

So using a 2000 Impreza RS for example, lets say we would like to know how much horsepower is needed to go 150MPH. Take .000007 times the frontal area which is 22 and the coefficient drag, in this case 35 times the target speed, 150 mph cubed.

.000007 X 22 X .35 X 1503 = 182

Car Frontal Area Cd HP Needed at 100 mph HP Needed at 125 mph HP Needed at 150 mph
2000 Subaru Impreza RS 22 0.35 54 105 182
2000 Subaru Impreza L 21 0.32 47
96
159
1998 Ford Mustang GT 22.5 0.34 54 105 181
1996 Honda Civic DX Hatchback 20.5 0.32 46 90 155
2001 Volkswagen Golf GL 20.5 0.31 44 87 150
1997 Acura NSX 19.2 0.32 43 84 145
2000 Honda Insight 20.4 0.25 36 70 120

Car Frontal Area Cd HP Needed at 100 mph HP Needed at 125 mph HP Needed at 150 mph
2000 Subaru Impreza RS 22 0.35 54 105 182
2000 Subaru Impreza L 21 0.32


1998 Ford Mustang GT 22.5 0.34 54 105 181
1996 Honda Civic DX Hatchback 20.5 0.32 46 90 155
2001 Volkswagen Golf GL 20.5 0.31 44 87 150
1997 Acura NSX 19.2 0.32 43 84 145
2000 Honda Insight 20.4 0.25 36 70 120