Search intensifies for children missing for two weeks from Victoria

A Victorian woman and her three children are still missing two weeks after she posted a worrying message on social media.

Police renewed their calls for public assistance to find the children on Thursday, and said a car mum Tracey Heuston was believed to have been driving had been found on Saturday.

The 49-year-old mum took her eight-year-old twins and an 11-year-old from their Watsonia home on June 28 and they have not been seen since.

In the early hours of that same day, Ms Heuston posted a message on Facebook saying other family members had caused trouble for her and her young children.

"They need to be reminded who there f****** with befor i depart this world ill be taking some 0ne or maybe 2 with me," she said.

Banyule Detective Senior Constable Dale Ward said that someone must have seen Tracey and the children or at least know of their whereabouts.

"It's not easy to disappear, especially if you have three children with you," he said on Thursday.

He pleaded for Ms Heuston to bring the children home to "return some normality to their lives".

Det Sen Cons Ward also confirmed a grey Mitsubishi Magna sedan Ms Heuston was thought to be driving was found in Alphington on July 2.