Fancy that.
A study in Ireland supports our view that there is no good reason to legislate to ban smoking in cars with children.
Researchers at the UCD School of Public Health, Physiotherapy and Population observed 2,230 drivers in Dublin and found the prevalence of mobile telephone use was 2.56 per cent compared to 1.39 per cent for smoking.
The study, published in the Irish Medical Journal, concluded that the "resources required for a ban in vehicles may be labour intensive for the yield in detection or prevention."
Although this is an Irish study, there is no reason to believe that the same research conducted in London (for example) wouldn't produce a very similar result.
See: Ban on smoking in cars would have little impact, says study (Irish Independent).
Update: Smokers’ group welcomes study showing low level of smoking in cars (The Journal.ie)