We have seen an increase in the number of people asking a recurring question, is it illegal to smoke in cars in Spain?
The short answer is no, not at the moment.
The confusion seems to stem from two sources. The first being a law which is aimed at preventing anything interfering with the driver or the act of driving. There might be a theoretical case where smoking could lead to distraction, but it is only theoretical, the law does not in any way mention smoking.
The second confusing factor comes from a law relating to smoking in a car whilst carrying children. Some countries, such as the UK for example, do have laws in place which makes this illegal. The law came into force in England and Wales in October, 2015, and in Scotland in December, 2016. However, in Spain, no such law currently exists.
Perhaps needless to say but smoking does of course pose a health risk to the occupants of a vehicle, and there are safety implications too. Anything which might be a distraction or a risk should be avoided, but within the constraints of law, you are currently free to smoke whilst driving.