To rotate a model you need to add a CFrame.Angles at SetPrimaryPartCFrame() it would look something like this
Car:SetPrimaryPartCFrame(CFrame.new(randomSpawn.Position) * CFrame.Angles(0,0,0))
and you would need to change the CFrame.Angles value to whatever position you want the model to rotate to, they need to be radians but you can simply use math.rad() with the degrees you want it to rotate.