Diesel Vehicles
In fact these vehicles are a good source of daily 'income' for the authorities and the traffic police. Hence, they will never ban them in reality. Courts are teeth-less.
I remember of a joke. A person landed at Delhi airport from Kabul. He told that he was the Shipping Minister of Afghanistan. The authorities were taken aback. One of them told: But there is no sea or ocean touching Afghanistan. The person replied: So what? Do not you have Law Minister, is there any Law and Order in your country? more