This habit is very practical for traveling comfortably, but in certain situations it can be punished.
When it’s hot and we’re on the road, we all want to drive as comfortably as possible. While using a sun visor or air conditioning is very useful for keeping the vehicle cool, we sometimes have certain habits that can, in some cases, be penalized. Indeed, many drivers tend to forget these little rules of the highway code, or ignore them because some of them are so little known.
In fact, many French people do it: while the driver stops to buy bread or do a quick errand and you are waiting for him inside the car, it is much more practical to wait (especially if the children are in the back and sleeping) provided that you leave the air conditioning running in summer or the heating in winter. But according to article 2 of the decree of November 12, 1963, leaving the engine running when stationary is prohibited. It specifies that “parked vehicles must have their engine off, except in cases of necessity, in particular when starting from cold”. Also, if you picnic on a motorway service station for example, leaving the engine on to cool the car before continuing on your way, you expose yourself to a 4th class fine, in the amount of 135 euros (reduced to 90 euros if you pay quickly).
Furthermore, according to Article R318-1 of the Highway Code, “motor vehicles must not emit fumes, toxic, corrosive or odorous gases, in conditions likely to inconvenience the population or compromise public health and safety”. Other countries such as Germany or Italy impose these same restrictions.
To avoid breaking the law, it is therefore advisable to park your car in the shade (if you are lucky enough to find a space), to leave the windows open to air out the passenger compartment for a few minutes before turning on the air conditioning and, of course, to take the children out of the car in summer.