Fifi no-one is suggesting you lie.

You entered a contract of sale with the car company and purchased a car from them and apparently took out finance in the form of a fixed loan agreement to buy the car. So you have a debt and a car.

It would then appear you have given the car to your parents, which it appears was always your intentions and they would pay you for the car.

There is two ways of looking at this

a) either you have retained ownership of the car (I note your Father is the registered keeper, but that in itself legally does not denote ownership)and ownership only will pass in full when your parents makes the final payment. This is essentially a contract of conditional sale and a trustee could allow the sale to be completed. ie allow your Father to retain possession of the car and make the final payments to your trust deed, or

b) you gave over ownership to your Father when he drove it off the garage and essentially you have given him a loan. So he is the owner but he owes you the money for the car. In which case your father is one of your debtors and the trustee in your trust deed has a right to recover the outstanding debt for the benefit of the other creditors.

Many agreements are not put into writing in Scots law and are not required to be, such as the selling the car. So the point is it appears clear there is some type of written agreement between you and your father and its the duty of the trustee to determine which it has been. The key question is was it you and your Father's intention that ownership of the car would pass immediately and he would have a debt to you, if so its a contract of sale and he is the owner and also your debtor; or did you intend it would only pass when the final payment was made, in which case you are the owner and the property, the car vests with your trustee and it is for him to decide whether it should be sold or the agreement with you Father should be allowed to run.

Scots law allows a car to be kept by someone in a trust deed, providing they have a reasonable requirement for the car, up to the value of £3,000. From what you have said you have no reasonable requirement for the car, so it is important to decide what type of unwritten agreement you had with your Father regarding the car.