Advance Income Tax paid at time of purchasing car, and Income Tax paid at time of registration of car are technically refundable, but its Pakistan baby, forget about refund, you will never get it, so just make it Adjustable, means, you can minus it from your payable taxes while filing your returns
For filing, always ask a professional to do it for you, I do it from a firm of CA qualified guys.
If you you do it yourself or ask a 500 wala guy to do it, you may get your name in ATL temporarily but you may get in trouble later on for incorrect filings, or you will have to go through Audit process and will cost you much more money