A roller coaster car is released from rest at point W. Calculate its speed at points X, Y, and Z. Neglect friction.?

You're going to make use of the conservation of mechanical energy here.  Let point W be at height hw, point x at height hx, point Y at height hy, and point Z at hz.  Note

hw > hy > hz > hx

Now the total energy the car can have is the potential energy at point W:

E = U(w) = mg(hw)

At point X the car has both kineitic and potential energy that add up to E so

mg(hw) = 1/2 m(vx)^2 + mg(hx)  -->  vx = sqrt(2*g*(hw -hx))

The same happens for points Y and Z

mg(hy) = 1/2 m(vy)^2 + mg(hy) ---> vy = sqrt(2*g*(hw - hy))

and   vz = sqrt(2*g*(hw - hz))

Is this s new Hyundai or Kia car?