How to use a motion study to calculate accurate velocity of object powered by gravity?

So, here is what i'm trying to do. I'm not sure if Motion can be used to do this or not.

I am designing a Pinewood Derby Car. I've created the car, the track, created the path mates and can simulate the car moving down the track's path

What i want to do, is determine what the velocity is of the car as i make modifications to it. Basically, i want to calculate the time it takes the car to travel down the track after each theoretical modification. This would allow me to study the effects of general weight placement in the vehicle, and overall design modifciations that COULD result in better performance.

I understand that this will not correlate to reality, as I cannot account for friction forces acting against the car, but this will allow me to study the effects on speed that design changes have in a relative manner.

Any ideas?

I thought this might be a fun project, and so i've been trying to work on it.

Thanks for any and all help!

Jeremiah

SolidworksMotion Studies