Power is the work done per unit time. The mass of the car is 1000 kg and work is done to increase its speed from 0 m/s to 25 m/s in 10 s.
The kinetic energy of an object with mass m and moving at v m/s is given by the expression (1/2)*m*v^2.
At rest, the kinetic energy of the car is (1/2)*1000*0^2 = 0 J. 10 seconds later it is moving at 25 m/s. The kinetic energy of the car is (1/2)*1000*25^2 = 312500 J.
In 10 s, the change in energy is 312500 J. The power required to achieve this is equal to 31250 W or 31.25 kW.