Most of the bass you hear coming from the car next to you isn't even being heard by the people in that car! This is because the brain needs the ear to receive at least half of the wavelength of the sound wave in order to understand it. If the brain can't understand it, it will be subconsciously ignored. The size of most cars only allows for the speakers to be about five feet from any given person in the car which means that the lowest sounds anyone in the car could hear would be ones with a wavelength shorter than ten feet. This means that the lowest third of the pitches humans can typically hear won't be recognized by the brain from inside a car. Not being able to hear the bass kind of defeats the purpose of having such a booming system. The bass can still be felt which can be a cool sensation but even that has its problems.
Listening to music with lots of loud bass can be potentially hazardous to one's body. Temporary and permanent hearing loss and internal bleeding are some of the downsides to listening to loud bass.
Everything has a resonant pitch that is dependent on the density, shape, and size of the object. Wine glasses are a perfect example. Have you ever rubbed the rim of a wine class with a wet finger to hear the ringing sound? The pitch that is created is called the resonant pitch of the glass and when you can hear the pitch the glass is vibrating at its resonant frequency. Resonant pitch and resonant frequency are the same thing only one is used to describe what you hear, pitch, and the other describes how fast the object is vibrating, frequency. Adding liquid to the glass or using a different glass can change what pitch you hear.
When I say that everything has a resonant pitch I mean everything; even your body. As a human body approaches its resonant frequency all of the different parts of the body begin to vibrate more and more violently like the wine glass and internal organs will rub against each other. The vibration will be most violent at the body's resonant frequency. After enough exposure the organs will rub each other raw and bleed. The resonant frequency of the human body is well out of the audible range and well below the capability of most car stereos but I would still be cautious because even if the bass is close to the right frequency the body will vibrate. If these vibrations can cause internal bleeding imagine what they are doing to your ears.
In order to hear something a sound wave must enter the ear canal. From there the sound wave hits the ear drum and sends a pulse through the fluid in the ear. Small hair cells are moved by this pulse and send the information to the brain for interpreting. Each time a hair cell is moved it is weakened and if one is weakened enough it can become useless. Hearing loss occurs as more and more hair cells are damaged.
The hair cells that best receive low frequency sounds are deepest in the ear and all of the hair cells on the way to the low frequency receptors will be affected by the pulse. Higher frequency sounds don't affect the hair cells deep in the ear. This is why the high pitch hearing is the first to go. When one listens to loud bass the stress on the hair cells is extreme because the music is loud and more of the hair cells are being damaged than when there isn't so much bass. If a person were to listen to loud bass excessively, total hearing loss would eventually set in because of the wear and tear on so many of the hair cells in the ear.
As a musician and music lover I feel that excessive bass is what it is, excessive, and my hearing is too important to me to let it get destroyed because I want to look cool. It is also pointless since most of the bass can't be heard from inside the car and why should I waste my money on a stereo system I can't listen to without getting out of my car. I also don't like the idea of internal bleeding. Even though it is unlikely, it still scares me. Please turn down the bass, for your own good.