Baking soda has been toted as a great odor remover.  If you’ve tried it, most likely you’ve been disappointed.  That is because baking soda is chemically formulated (its a base) to remove acid odors and performs poorly with other types.  There is one acid odor that is specially troublesome (from the stomach), especially if it is created in a car on a long trip :).  A friend of mine keeps baking soda and water in a travel sized spray bottle (the kind you can purchase to put hairspray in).  2 teaspoons in the tiny bottle is enough.  Shake it up and spritz on the odor and it should neautralize.  If the odor returns reapply as needed.  This works really well on baby spit up or sour milk too.