Have you ever stepped into a friend's car and wondered how they could ever let their interior become so disgusting? Most car enthusiasts love to keep their car spotless inside and out but an alarming number of drivers rarely clean out their car. CarRentals.com surveyed 1,000 drivers to see how often they clean out their car's interior. An alarming 32% of respondents said they only clean their car out once a year and an additional 12% said they never clean their car's interior. So, why is it so important to clean out your car? Well, it may be a lot dirtier than you think.

Roughly 700 strains of bacteria live inside of the average vehicle, meaning when you eat food in your car, you're exposing yourself even more to getting sick. If food spills into the interior and sits in the hot sun, bacteria can multiply and spread even faster. CarRentals.com even measured how many bacteria per square centimeter, or colony-forming units (CFU) there are on the average interior surface. The results are shocking.

The average car steering wheel was found to have 629 CFU per square centimeter. This is six times dirtier than a cell phone screen, four times dirtier than a public toilet seat, and two times dirtier than an elevator button.

Even if you clean your steering wheel frequently, it can quickly become dirty when you touch other public locations. For example, the average gas pump is 11,815 times germier than a public toilet seat, meaning every time you put gas into your car you are bringing countless germs into your car. Remember, this data applies to personal cars so rental and rideshare cars have even more germs in them.

In order to make sure your car stays clean, be sure to wipe interior surfaces, change your air filter, and vacuum the upholstery, and shampoo the carpets. Also, your car keys are the most commonly-touched accessory so make sure to wipe them down frequently.