Ya, I'm crayo. 2s/t^2 will only work for constant acceleration. If you're pushing the car I highly doubt it will be constant acceleration. If you use a sloped ramp, acceleration can be found quite easily (ignoring friction, but that should be minimal). Oh, in physics (or maybe engineering, I can't remember) s is displacement.
F= mg*sin(x) where x is the angle of the slope.
F=ma
mg*sin(x)= ma
a=g*sin(x)
If you accelerate the car that way you can easily find the final velocity since acceleration will be constant. it's simply v^2= 2as (measure the length of the slope).
What is the actual wording of the assignment?