Mrs Ryan bought the Mini in 2001 as a surprise for her husband's birthday.
She said she knew of one other Masterton couple in the rally who would be driving a Jaguar.
Participants will stop over in Tauranga, Gisborne, Napier, Wellington, Blenheim on the way to Christchurch and will be greeted by a mayoral reception at each stop.
The rally has been organised by the British High Commission and is fundraising for four New Zealand charities - the Starship Foundation, Save the Children Fund, Stepping Stone Trust and the Christchurch City Mission.
The event costs $450 to drive the entire course.