My friend is in a cast up to her knee for the next 5 weeks as she's broken her foot. She isn't very good on crutches, they kill her hands and arms and she generally gets tired! So on the london to brighton run this weekend we want to bring a wheelchair in the mini

Has anyone managed to fit one in the back of a mini before? Or got any good ideas of how to carry one? Bungle said about a bike rack!
Grateful for any advice,
amy