Final answer:
The toy car has an energy stored as kinetic energy of 0.5 joules.
Step-by-step explanation:
The kinetic energy of an object is given by the formula:

Given that the mass of the toy car is 500g (or 0.5 kg) and it is moving at a velocity of 3 m/s, we can substitute these values into the formula to find the kinetic energy:

Simplifying the equation gives:
KE = 0.5 J
Therefore, the toy car has an energy stored as kinetic energy of 0.5 joules.