with due respect i'd not recommend ppl in Pakistan to Rent-a-vehicle without driver.
majority of Rental car operators are con-men. - I doubt if AVIS & Hertz is still operating in Pakistan., however you please check from respective websites
Rent a vehicle in Pakistan with driver, The company's driver will be responsible for all trouble & arrangement of alternate vehicle in case of brake down. You pay fuel & agreed rental per day -
The absence of LAW, insurance issues & doubtful mechanical conditions of vehicles are HIGH risk if you choose self drive.