What do a Starbuck’s latte, pet urine and engine oil have in common? All three can raise a serious stink when they wind up on your car’s upholstery, cloth mats or carpet. When you detect a persistent mystery odor in your car, follow these tips:

• Clean and vacuum thoroughly. Besides wiping down hard-plastic surfaces with an ordinary household citrus cleaner or automotive specialty product, use your vacuum’s crevice attachment to get into every nook and cranny, including the bight (the crack where the seat back meets the seat cushion). You might find an ancient honey-mustard-drenched chicken nugget as the source of the smell. Sweep under the seats, too.

• Spread carpet freshener. For tobacco smoke, chemical odors or general mustiness, sprinkle baking soda or a borax-cornmeal mixture (1 cup borax, 2 cups cornmeal) liberally on the carpet. Give it about an hour to absorb the odor before vacuuming again. Stubborn smells might require a slightly more expensive weapon—zeolite, a porous, non-toxic volcanic rock that works wonders on many types of odors. Hardware stores carry it in packets or shaker cans for about $10. You also can place or hang a mesh bag filled with zeolite in the car to absorb odors continually.

• Attack the source. For remnants of spilled milk, urine or baby spit-up, pet stores carry solutions containing benign active bacteria or enzymes. They eventually devour or break down the organic material causing the smell. Spray the carpet lightly, taking care not to saturate it.

Mold or mildew requires moisture. If the carpet feels damp, first locate the source—torn weatherstripping around a window, for instance, or a clogged A/C drain. After fixing the water problem, attack the mold with a disinfectant. Mold from a serious water problem might require professional help.

• Check the filter.  A bad smell from the vents often indicates the need to change the cabin air filter. Most late-model vehicles have one, although few owners know about it. To see whether your car has a cabin air filter and how to change it, look in the owner’s manual under “cabin filtration,” “pollen filter” or “micron filter.”

Finally, if odors still linger in the vents, try spritzing an odor-neutralizer such as Febreze, Renuzit or Ozium into the air-intake vents outside the car at the base of the windshield. Then operate the A/C and heater to circulate the product.