There's a lot of headache associated with purchasing a used car in Pakistan.
Look for a car in good enough condition, verify the documents, deal with local mechanics and then transfer it over to your name - another possible headache.
Once it's in your possession, you're likely to find a host of issues with it, requiring frequent visits to the mechanic and haggling on labor and parts and wasting time overall. If you're new to Pakistan, you're likely to simply get ripped off without even knowing it. There's a chance you might end up on the side of the road with a broken down car until you find an issue that previous owner conveniently forgot to mention.
Then selling it is another headache where you've to deal with chaska parties, dealers and the rest deciding your car is half the price you bought it at. And once again, the transfer, ensuring it gets transferred to the new buyer.