Perhaps the owner thought the badge stood for Mini Power?
I like the comedy car badges that poke fun at prententiousness - my favourite at the moment is the spoof of the Nurburgring badge used by those who seek to impress others by suggesting they have driven on the famous and dangerous track but instead of saying Nurburgring underneath the shape of the circuit, the letters spell out 'Neverbeen' ! But perhaps I've not laughed so much since seeing many years ago on the back of a Ford...... 'Ford Sierra Codsworth'