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
MI5 face mounting pressure over claims the IS executioner 'Jihadi John', named yesterday as a London graduate, was known to them
Labour leader Ed Miliband is due to set out his party's plans on how it would cut tuition fees.
New drug driving laws are to come into effect next week, including laws on some prescribed medications.