If you’ve noticed a crayon-like chemical smell in your Euro model car, this is exactly what it is and what you can do about it.
If you own or rode in a BMW, Mercedes, Volvo, SAAB, or Volkswagen and smelled what you think is a 64-count box of Crayola crayons, you aren’t, in fact, imagining things and there’s a very specific reason it smells like first grade. It’s called “Thermoplastic Adhesive” and it’s used to seal, protect, and provide sound dampening for all different areas of a car, most notably under interior carpeting, behind speakers, under the rear decklid, in the trunk, and anywhere were two different materials need to bond (think carpeting to bare metal.)
If you’ve ever used glue guns with those glue sticks, you know that when heated above a certain melting point, those glue sticks turn to hot glue. You probably also notice a hot glue smell, not particularly offensive but very distinctive. That’s the same principle happening in your car.
On a hot day, that thermoplastic adhesive doesn’t quite melt but, temperatures inside your car do reach levels where it’s hot enough to allow this glue to off-gas. It isn’t harmful or anything so don’t worry.
In some instances, like a large number of ’90’s Mercedes, there’s a specific swatch of thermoplastic adhesive causing that crayon smell.
This W203 C Class owner, in an attempt to find that offending odor once and for all, narrowed that thermoplastic adhesive smell to an actual Transmission Tunnel Insulator made of the stuff. Linked here is what the actual piece looks like, it’s humongous!
For some cars like Volkswagens where it’s more prevalent, several Volkswagen owners and their experience with the crayon smell claim that the Thermoplastic Adhesive is all over, literally holding the interior together. A good spot to find this crayon smell on VW’s is in the headliner.
A BMW 3-series owner on this website had a lot of luck getting rid of most of the smell by removing all the tar-like rubber matting and sound deadening from behind his rear speaker deck and back seats. He then replaced what he removed with dynamat and dynaliner.
As to the why a lot of European cars smell like this, I haven’t come across an official reason yet. Redditor NgurenrDavid does give a convincing explanation, one that I agree with.
It’s from the environmentally friendly glue, adhesives, and sealant mandated by the EU and every German automaker followed suit since the 90s, hence the dreaded “old German car” smell. Later model vehicles don’t run into that issue.
How to get rid of that crayon smell
The only sure way to get rid of that crayon smell is to remove all thermoplastic adhesive from your car. That is quite impossible and not recommended.
If you do some research for your particular car you might be lucky and come across one or a handful of offending pieces where the smell is coming from.
Then again, you might find that embedded everywhere is thermoplastic adhesive and there’s not much you can do.
In that case, you’ll have to rely on the tried and true method of masking the smell.
You can try any of a number of whole car air re-fresheners which acts like a giant bug bomb, saturating your car with disinfecting chemical compounds. The one by Meguiars seems to work fairly well for general odor eliminating jobs.
Then there is any number of air fresheners to try, take your pick of the lot.
Love it or hate it, that crayon smell in your BMW, Mercedes, Volvo, Saab, or Volkswagen is part of your car, there isn’t anything inherently dangerous about its odor, and, if you can’t take out the source of the thermoplastic adhesive, you might just have to live with it.
Do you have any clever ways of dealing with this Euro crayon smell? Let me know in the comments below.