Medical leaders want to extend the smoking ban to cars after research found "compelling" evidence to support the move.
The British Medical Association says smoking inside a vehicle exposes drivers and passengers to 23 times more toxins than a smoky bar.
Children, the elderly and people with respiratory conditions are particularly vulnerable to the deadly affects of second-hand smoke in a restrictive environment.
Doctors say governments must be "bold" as smoking causes 80,000 deaths in England and six million worldwide every year.
Dr Vivienne Nathanson, from the BMA, said: "The current UK Government prefers voluntary measures or 'nudging' to bring about public health change but this stance has been shown to fail time and time again."