I've received a few emails requesting information about car rental smoking policy, so I did some research. This is information directly from the car rental company websites.
Please note, that as with all policies, I try to stay up to date... but that these can change at any time without notice. Always check with an individual company to verify any policy. See: Disclaimer
Alamo
All Alamo vehicles are considered non-smoking rental cars. Additional cleaning fees may apply if a vehicle is returned in a condition where it needs to be extensively cleaned and deodorized due to smoking. You should be able to find out more information on your rental car contract.
As of October 1, 2009, all vehicles in the Avis U.S. fleet are designated as non-smoking cars. If this policy is violated, Avis may apply a cleaning fee of up to $250. Details of the policy will be on your agreement.
All Budget vehicles are designated as non-smoking. Budget will charge a cleaning fee if the vehicle smells like it has been smoked in, when it is returned.
In 2011 Dollar made all vehicles in their US fleets (both corporate and licensee locations) non-smoking. A cleaning fee of up to $250 can be charged if a renter returns a vehicle that has been smoked in.
All vehicles in the Enterprise fleet are considered non smoking rental cars. Additional cleaning fees may apply if a vehicle is returned in a condition where it needs to be cleaned and deodorized due to smoking.
Hertz.com allows both smoking and non smoking rental cars... but they maintain:
.. they cannot be guaranteed at the time of booking and are subject to availability upon arrival at the location.
Note: They did not mention here, nor could I find out if there is a extra charge or cleaning fee associated with renting a smoking vehicle. That is usually location specific and you would have to contact a Hertz location where you want to rent from or you can try calling 1-800-654-3131 to see if the reservation agent has location specific policy information regarding smoking policy.
All vehicles are considered non-smoking. Additional cleaning fees may apply if a vehicle is returned in a condition where it needs to be extensively cleaned and deodorized due to smoking.