The boss distributed to them money that was for the office and he let them use their own cars

I work for a foreign agency in Cairo; all the workers are Egyptian and the boss is a foreigner. The boss distributed some money to the workers that was set aside for hiring cars for work to do with the office, so that the workers would use their own cars and let the office use them when needed. That was done as a reward to increase the level of income. This is not part of the policy of the head office overseas. Is this money halaal or not?.