I've got a spare one in the trunk

Auntie Gladys bought herself a new rear-engine continental car.

She took an old friend for a spin, but after only half a mile, the car broke down.

Both women got out and opened up the front of the car. 'Oh, Gladys,' said her friend, 'you've lost your engine!'

'Never mind dear,' said auntie. 'I've got a spare one in the trunk.'