I often travel to Dubai on business and rent cars from National and Hertz. Both companies fine you AED 1,000 (about $350 Canadian dollar) if you smoke in the car. National mentions it on contracts while Hertz tells you verbally when collecting the car. Hertz even takes it one step further and charges you for cleaning if you return the car with dirty/messy interior. I saw customers trying to get those fines/charges waived when returning the cars but both companies are very strict about these policies and ask them to pay the fine.