People who regularly travel along a similar route to the same workplace, school, university or other destination can car-pool, that is, travel together in the same car and thus save money and reduce fuel use and car emissions. They can either take turns travelling in each other’s car, or travel in one person’s car with the others paying petrol money. Parents driving their children to school can take turns driving other children as well. Car-pooling works best when people already know each other or have something in common such as their school or workplace. They will need to ensure that they can agree on matters like times of travel, punctuality, and smoking and music in the car. Workplaces and schools can encourage employees or students to consider this arrangement. Car-pooling appears to be mainly practised in developed countries,20 but there is no reason why it should not also be practised in the developing world.