If your car has ever harbored spilled coffee, a sick child, or a smoker, you know how hard it can be to remove a bad smell.
Mike Pennington, director of training and customer relations for Meguiar's automotive products, separates odors into two types: those for which the source is obvious and the rest. First, the obvious: Toss any leftovers or trash before they can stink up the car, and wipe up or vacuum any dirt you've tracked in as soon as you can. If a spill happens while you're driving, Pennington says, pull off the road safely and soak up any liquid with paper or cloth towels (keep some in the car) before it seeps into the car's fabric. If the mess has hit the floor, remove the floor mats and shampoo them as soon as you can at a hand car wash or at home using a solution of water and detergent. Test the cleaner in a small area first to make sure it won't stain. Household cleaners should work on most surfaces, but if necessary, buy a product designed for the surface you're working on—carpet, leather, or vinyl—at an automotive supply shop.
Room fresheners often just mask a smell, one expert told us, but industrial-strength odor eliminators purchased from a home or auto-supply store can chemically neutralize the odor and remove it. Other suggestions included leaving an open container of baking soda in a smelly car. Sprinkle it on the carpet and under the floor mats, then vacuum up what shows, and where it doesn't show, leave it. But make sure the surfaces are dry. "If the floor is wet and you throw the baking soda down," says a car wash manager, "it turns into rocks and will not kill the odor." From another car wash came another remedy: an open bag of coffee beans left in the car overnight. "It acts like a filter," a staffer explained.
A search for answers from National Public Radio's Car Talk hosts Ray and Tom Magliozzi to drivers of odoriferous cars yields more tips. A fishy smell? Could be antifreeze leaking into the car through the heating system. A smell that arrives when the A/C is first on? Check whether the evaporator drain is blocked. Mold from a water leak? Pull out the carpet and pad underneath, vacuum both sides, turn the carpet over, spray the back with a bleach solution or other fungicide to kill mold spores, then let it bake in the sun. (Our experts advise rinsing off the solution with water before drying the mat.)
What about spilled milk? "There is almost nothing worse than the smell of rotten milk in a car carpet," Tom Magliozzi once told a listener. He suggested selling the car to an unsuspecting dairy farmer.
Your own detective work (to find the smell) and elbow grease (to clear it) can save a lot of money. A professional detailer charges up to $1,000 for removing carpets and seats, and shampooing and steam cleaning a car's interior. That's enough to make any car owner cry over spilled milk.
A version of this article appeared in the September 2012 issue of Consumer Reports magazine with the headline "What's That Smell? Ridding a Car of Odors."