Police say they believe the vehicle belongs to Donna Graves, 61. Graves and her 29-year-old son Daron were last seen Thursday.
West division Staff Sgt. Patrick McCaffery said the vehicle matches the description of the Black 2013 Dodge Dart belonging to the Graves family.
Police have said one body was located in the car, but they have not been able to positively identify the victim.
The mother and son were last heard from as they left The Prior Sports Bar and Restaurant in Arnprior, Ont., at 11 p.m. ET Thursday.
David Graves, Donna's husband and Daron's father, said his wife had called him Thursday night and said they were on their way home, but they failed to show up.
Graves said he doesn't believe they drank too much and said it was understood that if someone needed a ride home, he would come and pick them up.
Over the weekend, grief counsellors were also at the Graves's home on Ferry Road, within sight of the recovery operation.
Dropping temperatures obstacle for dive teams
The police marine diving unit said a crane was expected to arrive in the afternoon to help remove the vehicle from the river, but the extreme cold is making the recovery difficult.
The windchill Monday is expected to make the temperature feel like –30 C in the Ottawa area, leading to a frostbite advisory. The cold can also cause fatigue among members of the diving unit, police said.
A lot of planning is needed ahead of time due to the cold, which delayed the beginning of the recovery Monday.
"It's not so much whether there is daylight remaining, but whether after the cutting and setup the divers are too fatigued to begin," said Staff Sgt. Marc André Sheehy.
Car located in river Saturday night
Police began investigating the river Saturday close to the home when they saw skid marks on the road and debris left behind, suggesting a vehicle struck the wharf and was in the river.
Dive teams located a car in the river Saturday night. Police at the scene said they were treating the incident as a car accident and said speed may have been a factor in the crash.
The vehicle had rolled over and was upside down more than eight metres underwater and about 40 metres from the jetty.
Channels will have to be cut into the ice to allow for cables to attach to the car, and then more ice will need to be cut to allow a crane to lift the vehicle out of the water, said McCaffery.
The coroner will not be at the scene until the car and body are removed, police said.