* Wind noise. The wind can create a lot of noise when it flows into your car through the open windows. This noise can be especially loud if you're driving at a high speed.
* Tire noise. The sound of your tires hitting the road can also be amplified when you have the windows down. This is because the sound waves don't have anything to absorb them, so they bounce around inside your car and make it louder.
* Mechanical noise. If you have something loose in your car, such as a piece of trim or a loose screw, it can vibrate and make a thumping sound when you're driving.
If you're concerned about the thumping sound when driving with the windows down, there are a few things you can do to try to reduce it.
* Roll up the windows a little bit. This will help to block some of the wind and tire noise.
* Turn on the radio or play some music. This can help to cover up the noise.
* Check for loose objects in your car. If you find anything loose, secure it so that it doesn't vibrate and make noise.
If you've tried all of these things and you're still hearing a thumping sound, you may need to take your car to a mechanic to have it checked out.
