#### ajdelange

##### Well-Known Member

- First Name
- A. J.

- Joined
- Aug 1, 2019

- Messages
- 2,000

- Reaction score
- 1,544

- Location
- Virginia/Quebec

- First Name
- A. J.

- Vehicles
- Tesla X Extended Range Plus 2019, Lexus, Landcruiser, SR5

- Occupation
- EE Retired

The manufacturer rolls the vehicle down an incline and from its speed and position vs time profile is able to determine coefficients@DucRider Curious if you saw a drag coefficient value for the R1T or R1S in this data you found? I did not see any and was curious how they would determine these number or if they are simple calculations of frontal area.

*a*,

*b*and

*c*that determine the force

*F = a + b*v + c*v*v*that retards vehicle forward motion as a function of its speed v. Those three coefficients are given to the laboratory that performs the test and are programmed into the dynamometer. Cd and A obviously influence

*a, b*and

*c*but so does rolling resistance.

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