The car was supposed to take the head of the Church to Castel Gandolfo, where Leo has repeatedly travelled on Monday evenings in recent weeks to spend a night and a day.
However, the papal journey was only briefly delayed by the car breakdown: The Pope got into an escort car after a few moments, ANSA reported.
The luggage was also hurriedly reloaded.
Leo took the opportunity to smile and greet the crowd that had gathered in Via Cernaia near Rome's main railway station.
There, the Pope had celebrated Vespers in the church next to the "Domus Australia" guest house and blessed a restored icon of the Virgin Mary.
While Leo's predecessor Francis often travelled in a white Fiat, the new Pope usually drives a dark electric Volkswagen.
Leo is also a passionate driver himself:"I remember that when I visited him in Chiclayo for the first time, he drove me around the city and the surrounding area, sometimes stepping on the accelerator quite hard," reported the Undersecretary of the Synod of Bishops, Curia Bishop Luis Marín de San Martín, in June from a visit to his brother in Peru.