The chair of the Royal College of Physicians' tobacco advisory group, John Britton, says the RCP is calling on MPs to support "this important health amendment".
The evidence shows the importance of protecting children from passive smoking, and cars are still a major area of exposure.
Such exposure is widely associated with adverse health effects, including an increased risk of respiratory and allergic symptoms. That is why the RCP is calling on MPs to support this important public health amendment.
But pro-smoking groups have said the restriction would be an "unnecessary intrusion into people's private lives.
More top news
A court has ruled that the original coffin in which Lee Harvey Oswald was buried belongs to his brother, not the undertaker's that sold it.
Manic Street Preachers lyricist went missing nearly 20 years ago but mystery still surrounds exactly what happened to him.
Deputy Prime Minister admitted he wanted to hit David Cameron on more than 20 occasions on late-night chat show 'The Last Leg'.