In 2009, Budget and Avis announced they had banned smoking in all their North American rental cars. Anyone who returns a rental car in which someone has smoked will be liable for a $250 cleaning fee.

Now that this additional source of revenue has been identified, other car rental companies are likely to follow suit.

This is good news for people who rent cars, use electronic devices that require charging, such as cell phones, and would like to use the cigarette lighter to charge them.

In the past, many rental car companies have disabled the cigarette lighter to prevent smoking in their cars, a hurdle that inconvenienced many electronic device users but was easily bypassed by a smoker with a book of matches or their own lighter.

Rather than trying to reconnect a disabled cigarette lighter, gadget users should request a working lighter when they rent the car, which should be easier to do now rental car companies can stop disconnecting the cigarette lighter and assess an extra fee.

Avis says when a vehicle is returned, the return agent will inspect the vehicle for physical evidence, such as ashes, butts and cigarette burns, and take photos to substantiate the cleaning fee.

If a vehicle that was smoke-free when rented is returned with tobacco odor, Avis says it will undergo special cleaning and the fee will be assessed.

This means Avis customers should do a sniff test, too, before driving out of the rental lot, and refuse to accept a car that has even a whiff of smokiness.

Renters of cars in southern cities, such as Orlando, Fla., should be especially careful when doing the sniff test, as adults in southern states smoke more than anywhere else in the country.