48, was last seen at around 8.15pm on October 1st on Bolesworth Close in Chorlton.
Police believe she may have walked to the Ivy Green area of Chorlton into the woodlands.
She is described as 5ft 3ins tall, of medium build with blonde shoulder length hair.
Christina was last seen wearing a blue Fat Face parker coat with a beige fur hood, grey jeans and purple wellington boots.
Detective Inspector Lisa Ogden, of GMP’s City of Manchester division, said: “Christina has now been missing for over two weeks and we are really keen to speak to the occupants of the car pictured as part of our enquiries.
“I appreciate the picture isn’t of the best quality, but it was parked on Ivy Green Road between 8.05pm and 8.40pm the night Christina went missing and I believe the occupants could have been walking in the area.
“I want to stress that they aren’t in any trouble but they might have seen something that could be incredibly helpful to our search but haven’t realised this.
“Christina has been known to travel in to Cheshire in the past so we are asking people in that area to also look out for her wherever possible.
“I would urge anyone that knows who the car might belong to or anyone who has any information about where Christina might be, to please get in touch so that we can reunite her with her family who desperately want her back home with them.”
Anyone with information about Christina’s whereabouts is asked to contact police on 0161 856 6031 quoting reference number 2085 of 01/10/2018.
Reports can also be made anonymously through the independent charity Crimestoppers on 0800 555 111.