The Unexpected Place That's The Dirtiest Part Of A Rental Car (And It's Not The Steering Wheel)

There are a lot of things to worry about when you rent a car on vacation: Which rental agency has the top marks across the board? Should you get that extra insurance? Is it better to prepay for your rental, or is that costing you more money? Heck, if you're overseas, you even have to factor in the difference between the local currency and the dollar to make sure you're not breaking the bank with gas. What you may not be thinking about is how dirty your rental car is, or which place in that car is the germiest. You might assume the dirtiest spot is where human hands go — the steering wheel — but that assumption would be wrong. In fact, the dirtiest place in a rental car is the trunk. 

In a 2025 study conducted by Scrap Car Comparison and Aston University, Senior Lecturer in Microbiology Dr. Jonathan Cox and his team tested samples from five used cars that were different ages, taking swabs from the trunk, the driver's seat, the gearstick, the backseat, the dashboard, and the steering wheel. Believe it or not, the steering wheel was the least germy, with only 146 bacteria found. Cox explained, "Due to increased sanitizer use since the COVID-19 pandemic, the driver contact surfaces generally didn't have the level of bacteria that we were expecting, meaning that areas such as the steering wheel were not as contaminated as they might have been a few years back." However, the trunk had an astonishing 1,425 germs. 

The study suggests that we're cleaning our hands more, which is great. In fact, the other spots in the car that are most likely to be touched by human hands aren't as bad as the trunk, either. The dashboard had 317 germs in the study, while the gearstick had 407. The backseat had even less at 323, which is surprising, as that's often where little kids tend to sit. The driver's seat was pretty gross, with 649 germs identified, but considering that you may be out sightseeing, and sitting on dirty fountains and chairs, transferring some bacteria over to the car seat makes sense.

The trunk, however, has more than double the number of germs as the driver's seat, and for good reason. You're likely putting your luggage there, which has been dragged around airports, put on the floor of hotels, and shoved in plane overhead bins, which are dirtier than people realize. If you're out hiking and get muddy, you may put your family's soiled boots back there or other dirty items that you don't want to put on the seat upholstery, particularly in a rental car. 

So, what can you do to keep yourself healthy? First, bring hand sanitizer and disinfectant wipes if possible. When you pick up your car, wipe down the dirty areas and other places your hands touch. If you plan to stow something in the car that you don't want to get dirty, throwing a towel or sheet over the bed of the trunk may be helpful. Finally, use the old standby of washing your hands frequently to avoid getting sick.