BERLIN -- Mercedes-Benz is making a greener, hybrid Popemobile for Benedict XVI, the German weekly Wirtschaftswoche reported Saturday.

However, a Vatican spokesman denied the newspaper's prediction that it should be ready for Benedict's visit to his native Germany in September.

According to the report, the new Popemobile will be based on the four-wheel-drive M Class Mercedes with a hybrid electric-gas motor.

The rechargeable lithium-ion battery will allow it to drive 16 miles without any polluting emissions.

The pope would not be allowed to use a purely electric car because the Popemobile must have the capacity to take off swiftly in case of emergency, according to the report.

A Mercedes-Benz spokesman said the group could give no details on its private clients "for reasons of confidentiality."

Mercedes has provided the special cars to successive popes since the 1980s. The large-windowed, reinforced glass design allows for maximum viewing with high levels of security.

Last December, Cardinal Giovanni Lajolo, the president of the governorate of Vatican City State, suggested that Benedict was "prepared to use an electric Popemobile" as long as it was efficient and reliable.

Benedict XVI, sometimes labeled "the green pope" in the Italian press, has emphasized the defense of "God's works" and therefore the need to protect the environment.

Vatican spokesman Federico Lombardi told AFP on Saturday that while the project for the new car was under development, it was not yet finalized and that the vehicle would not be ready before the end of the year.