The missing Saint Mary’s University student was last seen Feb. 13.
Sgt. Nancy Rudback said the major crimes unit interviewed the driver on Saturday night. But she won't say if the driver provided any useful information.
Saunders's car was found in Harrow, Ont., near Windsor, on Tuesday.
Her roommates, Blake Leggette, 25, and Victoria Henneberry, 28, have been charged with possession of a stolen vehicle and fraud.
The fraud charge against Leggette is connected to the use of Saunders's bank card.
Search efforts ramp up
Saunders's brother flew to Halifax on Saturday to join a legion of volunteers trying to find her.
They plan to plaster Halifax with more than 1,200 posters with photos of the Inuk student from Labrador. The volunteers are working in an Amnesty International office because they have no other space.
"One of the things we really need at this point is to locate a space where people can gather and where we can make materials available to distribute them around the city,” said Darryl Leroux, Saunders’s thesis supervisor.
More than $11,000 has poured into an online fund to pay for the posters and the costs of flying her family to Halifax.
"We believe this is a worthy cause and we're hoping that with our donation that we'll be able to assist in a happy ending in this endeavour,” said Smitty’s restaurant manager Lorraine Houston.
Saunders had just submitted her honours thesis proposal focusing on missing and murdered aboriginal women.
"She started doing more reading and talking with people in her family and also people in the Mi’kmaq community in the Halifax area and it really started to crystallize for her and having those conversations, sort of personal healing nature of the research, really came to the fore,” Leroux said.
He said the ordeal is hard on the volunteers and some are seeking crisis counselling.