To find the initial speed of the car, we can set up an equation using the given information and solve for the speed. Then, we can check the options to find the correct initial speed.
Let's assume the initial speed of the car as x km/h.
According to the given information, increasing the speed by 10 km/h saves one hour in a journey of 200 km.
So, the time taken to cover 200 km at the initial speed is 200 / x hours.
And the time taken to cover 200 km when the speed is increased by 10 km/h is 200 / (x + 10) hours.
According to the question, the difference in time is 1 hour:
200 / x - 200 / (x + 10) = 1
Now, we can solve this equation to find the value of x.