The old E36 are very good cars, except for a few problems
1 - their rear shock mounting area will tear out from the car over time (repair that immediately with new sheet metal "RIVETED" to the body and sealed.
2 - The ECU holding case used to get flooded with water if the wiper tray drains got blocked with dirt and leaves etc.
Most of them in Pakistan are now missing the entire front plastic underpanels, mudguard shields and also a lot of clips to secure the wirings in the engine room, They have also suffered nitto ustadee from time to time. The rear supension bushings would be gone to hell and would require replacement (pricey in Pakistan as the parts are priced in Euros and not Yuan) - your mechanic also would need to own a torx (male and female) set, all metric sizes sockets and and spanners including S spanners and Torque wrenches if you want to have a reliable car.
Otherwise the car will require 20 hours of work for every 10 hours of driving.