The 85-year-old head of the Roman Catholic Church was given two models of the new white Class M car - which has bullet-proof windows and runs on unleaded petrol - at a ceremony in the Vatican gardens.
Benedict was expected to take one of them for a spin for the first time on Saturday, when he visits the square at the Spanish Steps in central Rome for an annual ceremony celebrating the Immaculate Conception.
"It's a joy to be able to accompany Benedict XVI on his journeys. It's an important commitment which we carry out with passion," said Dieter Zetsche, chairman of Daimler, the German company that owns the luxury Mercedes-Benz brand.
Popes have been using Mercedes cars for over 80 years, he said.
The new model has been lowered by a few centimetres to make it easier to transport by plane when Benedict travels abroad. The air-conditioning and lighting have also been improved in a bid to help the head of the world's 1.2 billion Catholics relax during long trips.
Mercedes has provided the special cars to successive popes since the 1980s, the high-sized, reinforced glass design allowing for maximum viewing with high levels of security.
Bullet-proof windows were added after Turkish assassin Mehmet Ali Agca shot and wounded pope Jean Paul II in 1981.