Congratulation, encik.
SInce your FETs running well now, why dont you make a piece of PCB to mount those FETs properly and put the heatsink over them before they got short/damage by the vibration the car. I've been through in that case and my FETs got burnt out.
Do you mind to sketch your mod's and post it to here?
Anyway, no one sell the 4562 here but some people had them on their Z already. I wish I can put 4x2 on my board.
Salam.