I don't think there would be a problem with assume of mortgage provided there is good faith between buyer and seller.

The seller will execute a conditional deed of sale at first while the car is not yet fully paid with bank. An absolute deed of sale follows upon full payment and release of mortgage will have to be made.

Armed with OR/CR, Release mortgage document, and Deed of absolute Sale, the buyer may then proceed to LTO and register the car in his name.

The car will have to be fully paid first before any act of transferring.