Deputy Prime Minister Bill English says he became aware of a rule that ministerial self-drive cars should stay in an MP's primary place of residence only when it was changed.
Prime Minister John Key altered the rule in May, allowing Ministers to use the cars in Wellington rather than their electorate.
Mr English, along with about 10 other ministers, has benefited from the change.
He says a self-drive car is part of the package for all ministers and it was delivered to him in the capital.
Mr English says he understands the rule was changed to accomodate a number of ministers with families in Wellington, and he never lobbied to have it changed.
He says Labour has raised the issue to distract from problems over leadership in its caucus.