The Sûreté du Québec released a description of the car, a decade-old Chevrolet Cavalier, today in the hope that someone may be able to identify the vehicle.
Bonnette, a waitress at the Vegas Tour bar, was last seen closing up the establishment just after 3:15 a.m. ET on June 24.
According to a witness, she met with a bar owner before she left and drove off alone.
Her burning vehicle was found two hours later.
The car, described as a light beige or grey coloured, was spotted in the area of the bar at around the time Bonnette was last seen, SQ Sgt. Benoît Richard said.
It was also seen on the street next to where the burning car was found by a passerby.
Police canvassed the area and set up a command post at the bar in the days following the discovery of the body.
Richard said investigators reviewed security cameras in the area and spoke to several witnesses.
"We did get a lot of information from everything," he said.
"The investigation is progressing quite rapidly, and we could have some new information to give out in this case in the next couple of weeks."
Police are asking anyone with information on the vehicle to call 1-800-659-4264.