I don't have any experience with Stink Bugs in cars, and I do think this is a great recommendation, but if you don't know DE, be careful when spreading in the grass areas around your car. Don't do it in the wind, it kills bugs because it microscopically cuts them. If the wind blows while you're putting it out and you breathe it in, it will cut up your lungs as well.
- Diatomaceous Earth: Sprinkle diatomaceous earth around your vehicle if you park in the same spot regularly. This natural powder can help kill stink bugs.
Great to use, I use it for my pool filter, just be aware and careful, maybe use a mask (and no, I'm not a mask guy, ha)