Mystery "Coffee" or "Coke" - like Stain/Spotting on My Interiors

On both my '97 Taurus and '02 Impala, I have this mystery brown spotting appearing all over the interiors of both cars. It kind of looks like someone shook up a Coke and then opened it, or pulled a straw out of a coffee causing droplets to be sprayed around the interior. The spots are various sizes (as large as a dime and as small as a pencil tip). It’s mostly on the fabric - the seats and rugs, but I’ve also seen tiny specs on the dash. It always washes out of the fabric with Spot-Shot, and the dash blemishes wipe right off (they’re kind of guey like dried-up Coke would be), but it’s always been a mystery to me where these spots are coming from. Before I bought the '11 Equinox, the wife drove the '02 Impala and I was driving the Taurus. I wouldn’t see this spotting in my Taurus, but whenever I cleaned the Impala, I would see it in her car and so I’d ask her if she (or the kids) was spilling coffee or spraying colas around the interior. Answer was always “no”. Well, I had been doing work on my Taurus for several months and the car was just sitting all that time. Today I finally cleaned the interior of all the junk I was storing inside while working on the car, and I saw this spotting all over - on the carpeted mats, underneath the carpeted mats, and the seats (although not as pronounced).

Does anybody know what causes this? It just seems to appear on its own. Could it be an indication of coolant in the air? I’ve suspected both cars of having a heater core leak, but I don’t see any leaks in either interior. Could fumes be coming through the vents but not leaking/dripping on the interior? I can smell fumes of some kind in the Taurus, but not the Impala. I doubt coolant could be causing the stains, but I was thinking maybe it was acting kind of like the way law enforcement uses SuperGlue to fumigate and lift fingerprints, accenuating existing stains by contacting them in fume form.

I don’t know, but it sounds like ectoplasm. You may have to call Ghostbusters.

Any smokers in the car ?

Where do you live?
It sounds to me like there is some form of insect getting in the cars.

I would vote for spilled soda pop products with the sugar attracting dirt. Any Chance? I clean almost everything with scrubbing bubbles.

Or some strange form of mold/mildew/fungus since it’s “growing” even under floormats. But I’ve never heard of brown mold.

Some kind of condensation of fumes?

Mold can have a white, grey, green, blue, brown, or black color. Depends on the species.


If your brown spots match the ones pictured in this article, it’s mold/mildew:

Since the car is completely infested, simply washing the spots away won’t stop them from regrowing. Once established inside/underside carpets and upholstery, you may not be able to eradicate it. But try the methods in the article.

I agree with TSM. Since the stains are also under the mats and mostly on the fabric, you might have some type of insect infestation.

If insects were leaving brown spots all over the inside of the car, there would be dead insects all over the inside too. It’s mold/mildew.

My bets on mildew

Try this: scrape some of the brown deposit into a sealed container and bring it to your state’s Department of Agriculture office. Request an identification of what it is. They have the expertise and lab to identify it, and their services are free.

I used the services of the one in NH some years ago to identify a strange bug, and they sent me a comprehensive written report, including where they nest how to eradicate the pests. My guess is that you’ll get the same results. Their budget allocation gets validated partly by how much assistance they provide to the local communities.

A first step , before sending it off to be analized…
Wipe it …dab it… with a wet paper towel and…
Smell it .
Coffee ?
Coke ?
smoke ?
mold ?
This will give you a clue at least.