Allowance of Km and Liters. This differs from posts and departments/directorate, e.g. senior commands have more allowance, similarly Intel agencies have more allowance and vehicles. Different allowance for staff car, broad arrow unmarked vehicle, green plate and military vehicle. Units and HQs have different allowances. Under these, the vehicle can be used for official and personal use. Some commanders dislike personal use so officers under them do the same, while other allow it as per regulations. Some vehicles have restrictions from leaving cantonment, some have restrictions leaving the stations, where as others are free to roam the country, depends upon nature of post and directorate. Military vehicle can also be hired on payment.
For staff car, an indent is made and sent to GHQ for use outside station. Some have more than one staff cars. Some have marked staff cars/SUV with formation signs, other have unmarked with star plate. Some have both. Others have green number plate ones also. And the fourth category has civilian cars/SUVs with civilian number plates.
Use of military vehicles have decided promotions of officers also, there was a GOC 17 infantry Division. His daughter was studying in Lahore, the staff car took her to Lahore. At night the car got stolen outside a restaurant. The driver said the daughter took it with her friends. Posting came for GOC to GHQ and then retirement.
Those who make money through contracts/forging/passing information don't survive long. FIU, CMI etc are for for this purpose.