Law of Conservation of Energy said that Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. By winding the spring on your mousetrap car, you store energy in the spring as potential energy. This stored potential energy will convert energy into kinetic energy as the mouse-trap car begins to move. But there is friction and in order to overcome friction you have to do more work.
Friction converts energy into heat and sound which takes away energy from your motion, causing the car to stop as its energy is turned into other forms. When designing a mousetrap car, there are two variables that truly determine the overall performance: friction and energy. If my mousetrap car has too much friction, the energy in the spring will be turned too quickly and my mousetrap car will not travel very far or accelerate very fast. The smaller the friction is, the farther the mousetrap will move my car. It your car has a force advantage, then your car will move super fast