# At what M.P.H. do the aerodynamics of a car begin to affect its speed?

I need to know for a science project, in which my friend and I are doing the question, "how do the aerodynamics of an automobile affect its performance and speed?" I greatly appreciate any help given- thank you all so much for your effort!

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• Max J
Lv 5

Technically, if an object is moving aerodynamics will affect performance. Because flow restriction of a fluid is proportional to speed squared, it generally just kind of works out that around 30 miles an hour there is a significant increase in how much affect further increase in speed will have. Most cars are designed to optimally operate around 30-40 miles per hour, as that tends to be the average speed for driving in cities, where gas mileage is worst. In rare types, such as solar race cars, the car is designed to run optimally at highway speeds with electric motors. Formula cars are optimized to run at speeds in excess of 100 miles per hour to achieve peak engine efficiency. The aerodynamics can be adjusted depending on the designed function of the vehicle, however other design factors often come into play, such as cargo capacity, driver comfort, passenger number, and so on. For instance, getting a vehicle to comfortably seat 6 people that has the same aerodynamics as a solar race car would be nearly impossible because of the minimum aerodynamic cross section of the vehicle. This cross sectional area is one of the major factors that will affect aerodynamics.

Source(s): Kansas State University Solar Car Mechanical Team leader.

I would think that any speed of the car would have some kind of effect on displacement of any fluid; in this case the fluid is air. The quantity of air displaced would depend on the aerodynamic shape of the car.

• 4 years ago

i've got been pulling my hair out with a knocking noise in my 206 for the final 2 days. Ive had 4 mechnics attempt force it and am additionally a mechanic. It starts off at approximately 10kph and forestalls in case you drop the grab. looks like its coming from the rhs. i'm suspect of the gearbox yet its on the lhs. It looks like something rubbing on the shaft or a unfastened timing belt, yet thenoise isn't there rolling in impartial or in kit working up on jacks. Any concept. Regards Andrew

At what speed do they BEGIN to affect? As soon as it is not stationary.

If you had say 50 lbs drag at 50 MPH, at 100MPH you would have 2500lbs drag.