Legislation introduced in October 2015 states that any driver or passenger who smokes in a car with a passenger aged under 18, is liable to be hit with an on-the-spot £50 fine. However, no fines have yet been recorded.
According to the BBC, only three police forces have reported incidents of adults smoking in cars and all were issued with a verbal warning.
Metropolitan Police, issued two warnings, Dyfed-Powys Police, issued four and Devon & Cornwall Police issued one.
However Deborah Arnott, chief executive of Action on Smoking and Health (ASH) told The Huffington Post UK a lack of fines doesn't necessarily mean the legislation isn't working.
"Making smoking in cars a subject of legislation creates a deterrent and gives children the right to challenge adults who smoke in the car they’re travelling in," Arnott said.
"Research by ASH, carried out after the legislation came into force, found 86% of children said they weren’t exposed to smoke in cars and only 3% said they were exposed most or every day, so lack of fines is not a sign the legislation isn’t working.
"Police and local authorities have now agreed new guidance on enforcement, which clarify their roles and responsibilities in future joint working, but enforcement by fining is a last resort.”
Arnott reiterated that parents should not smoke in cars with children.
"The high levels of smoke concentration in such a small space are seriously harmful easily reaching 11 times that in a pub before the smokefree laws came into effect," she said.
"Tobacco smoke is a known cause of respiratory diseases, glue ear and worse still sudden infant death syndrome, and it’s harmful for everyone, not just children.”
Dr Helen Webberley, dedicated GP for www.oxfordonlinepharmacy.co.uk added: "We are all too well aware of the dangers of tobacco smoke both for the smoker themselves and those around them who, through passive smoking, have an increased chance of developing chronic lung disease, heart disease and cancers.
"We know that children from smoking families are more likely to suffer from lung infections, ear infections, slow growth and have a higher incidence of hospital admissions.
"Smoking in a confined space such as a car, even with the window open, exposes the other people in the car to smoke and all the negatives associated with it.
"Modern children are very aware of the dangers of smoking and should not be made to breathe the smoke of others."