I know you've had this experience, too -- you hop in a rental car after a long flight only to be hit by something incredibly foul-smelling. If you've ever been unable to put your finger on the cause of the olfactory disturbance, check out this article from Elliott.org and see if you can finally figure out what offended your nose.
Travel can be an olfactory experience, by which I mean everything smells. Even your rental car. Hertz recently teamed up with Fresh Wave to use its IAQ technology to eliminate unwanted odors in its cars.