"Maybe one of the ways we could do better is to encourage people who see people smoking in cars, tooting to them and doing the 'you shouldn't be doing that, mate' [gesture]."
She wagged her index finger in a scolding gesture to demonstrate how this could be done.
Mr Lees-Galloway made the call on World Smokefree Day, saying it was Labour's policy and the Government should adopt the initiative.
"Not only does it protect youngsters from the damage caused by secondhand smoke, it helps to denormalise smoking by reducing the opportunities for children to be exposed to cigarettes."
Mrs Turia has driven many of the anti-smoking measures the Government is now putting in place, including hefty tax increases on tobacco in the latest Budget, requiring retailers to store cigarettes out of sight of customers from next month and introducing plain packaging.
She said although Labour was now urging more action on smoking, it had had nine years to make such changes itself but had done little.
A spokesman for the lobby group Ash agreed with Ms Turia's solution as well as the suggestion for a ban to reduce the exposure of children to secondhand smoke.
"I think most of the public is on board with that message anyway. There is only a small minority for whom that message hasn't sunk in."
He did not believe it would prompt cases of road rage, "not any more than we've got at the moment anyway".
He said there was no reason a ban could not be introduced here, saying it would be similar to policing the cellphone ban, but with the added factor of establishing any children in the car were under the set age - which was 18 or 16 in most countries with a ban.