Police said a 64-year-old man found the oil paintings at the rest stop near Ohrenbach in central Germany last month.
He later handed them in to police in the western city of Cologne.
An initial assessment by an art expert concluded the two framed paintings were originals, police said.
One is a self-portrait by Pietro Belloti showing the Italian artist smiling and dating to 1665.
The other is a portrait of a boy by the 17th-century Dutch artist Samuel van Hoogstraten, date unknown.
SOURCE: The Associated Press