If the two bumper cars collide, they will bounce off of each other.
After the collision they both move in the opposite direction but with same speed as before.
You can see that in the video.
The two bumper cars have the same mass. Because of that they exchange their velocity. The kinetic energy before and after the collision is the same, nothing is lost.
But without the elastic spring at the front of the car, kinetic energy would be transformed into a different form because of the deformation (then both cars would move with less speed than before).
Because of the springs, the collision is an elastic one.
Elastic collision always means that kinetic energy is conserved. Further we can also see that the momentum is conserved in collisions like that.
