if u are driving and smoking just crack the windows a little [Window visors are a life saver] and it wont smell within an hour i find. but if u hot box the msell usually lingers for like 24 hours, there is NOTHING worse than waking up in the morning to go to work with the smell of wet weed in your car
As people said depends on yor vehicle and the materials. If you roll your windows down it will minimize your problems. The faster your driving the better circulation. "Chonging" out your vehicle can leave the stench for several days. If you ever get caught in a bad situation like being pulled over with the stench, then i have a suggestion. Keep an emergency cig or even better a black and mild in your vehicle. Light it up and puff it as much as possible before the cop comes to your vehicle. The tobacco smell should cover up the smell of pot pretty well. Taking a few hits of tobacco is better then being arrested trust me. Of course keep in mind not to do this if your not 18 or above. But id say the best advice is to keep your windows rolled down and you can avoid the scent most of the time.