My dad had a will, but to apply it would involve appointing a lawyer (extra costs) especially since my siblings and I were not claiming any of the assets and it will all go to my mom.
Basically what we did was that we went to the Harta Pesaka route. All my siblings and I signed of a form at the Magistrate's Court that we are not making any claim to my fathers assets.
Next my mom completed the Harta Pesaka form and submitted it to the Court. Waited a couple of months and the Court released its verdict. After that we finished up with the land office (transfer of property), bank (transfer of cash) and JPJ (transfer of vehicles). All in all, completed within 1 year.
Btw, sorry for your loss.

Oops, sorry to add on.
If you do go down the transfer vehicle to your own name before selling route, you may end up with 2 names (your dad and yours) on the registration card. Some people may not like since it becomes "third hand". You may want to check the process on how the executor of the will (once Harta Pesaka comes out with the results) is able to sell of the car.