Can they take my dad's car parked on my open driveway, for my debt?

No

The bailiff may take control of goods only if they are goods of the debtor.^[1]

If a bailiff takes a car belonging to some else, they can make a third-party claim.^[2][3][4]

The owner of the car may recover damages for the loss of use of his car,^[5] and recover his legal costs for bringing the claim.^[6][7][8]

^{[1] Paragraph 10 of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[2] If the debt is a not High Court writ: Civil Procedure Rule 85.6
[3] If the debt is a High Court writ Civil Procedure Rule 85.6
[4] See Making a third-party claim to controlled goods
[5] Section 3 of the Torts (Interference with Goods) Act 2007
[6] Civil Procedure Rule 44.2
[7] Civil Procedure Rule 46.5
[8] Practice Direction 46 - Costs Special Cases}