Can bailiffs take a car from closed private garden?

No

Bailiffs cannot break open a locked gate or entrance to domestic property.^[1]

If the garden is not where the debtor usually lives, the bailiff is unable to take control of the debtor's goods there,^[2] unless the bailiff applies to the court for that authority separately.^[3][4]

^{[1] Paragraph 17 of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[2] Paragraph 14(6) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[3] Paragraph 15 of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[4] Civil Procedure Rule 84.9}