Do You Need to Wash Your Car's Undercarriage?

dad and daughter washing car
If you don't go to a professional car wash to have your undercarriage washed, consider using a pressure washer to get at those hard-to-reach areas. KOLOstock/Getty Images

We've already talked here about the importance of washing your car regularly. But how often do you wash your car's undercarriage when you give your car a good scrubbing? Never, right? Well that's probably not the best answer if you're at all concerned about the life of your car.

Mercedes-Benz knows the importance of an undercarriage bath. The luxury carmaker even included a new Carwash function on its 2020 GLS-Class SUV. When drivers select the Carwash mode, the SUV automatically raises its adjustable suspension system to its highest setting so water and soap can access the underbody and wheel wells. The Carwash mode also closes the windows and sunroof, tucks in the side mirrors, turns off the rain-sensing windshield wipers, and aims the camera system so the driver can more easily guide the vehicle onto the tracks of an automated wash bay. Upon exiting the carwash, the Mercedes automatically turns off Carwash mode. It's pretty brilliant.


To Wash or Not?

Of course, we don't all drive these new Mercedes SUVs. But you do need to keep your car's undercarriage clean. So if you're simply washing your car to maintain its good looks, that's probably not enough. In fact, Consumer Reports says in addition to washing your car whenever it's dirty, you should also get an undercarriage wash at least once a season, and even more if you indulge in activities like off-roading.

Car care product manufacturer Dr. Beasley's takes an even more aggressive stance on how often you should wash your car's undercarriage. For instance, if you drive in areas where roads are salted, Beasley's recommends removing that salt residue as soon as possible because the longer it's on your car, the longer it's reacting with the elements that create corrosion and rust. That goes for those living and driving in coastal areas, too. The air carries salt from the ocean, and it will gradually have the same effect as salt brines dumped on roadways.


DIY Washes

If you prefer to wash your car's undercarriage at home instead of at a car wash, Beasley's suggests you invest in a pressure washer and a good degreasing agent. The pressure washer can easily reach areas that you can't — or wouldn't want to — reach by hand, and the degreaser will ensure all the surfaces are rinsed clean.

Beasley's provides additional tips for DIY undercarriage washing, including:


  • Consider lifting your vehicle with jacks or ramps (but make sure it's stable)
  • Remove your wheels to get better access
  • Check your brake and fuel lines for signs of corrosion, as they tend to rust the fastest but are also crucial to the car's safe operation
  • Lubricants like WD-40 can help protect a clean surface
  • Don't apply products like rubberized undercoating protectant unless the car is completely dry

So can we expect to see features similar to Mercedes Carwash mode on other new vehicles in the future? It's hard to say. In the meantime, keep in mind that washing your car's undercarriage takes only a few extra minutes and the benefits are worth the effort.


Car Undercarriage FAQs

How often should you wash your car undercarriage?
Experts recommend that your car undercarriage should be washed at least four times a year, as in, once for every season of the year. This could be more if you take the vehicle off-roading or live out in the countryside where the roads are not paved.
Do car washes clean the undercarriage?
Yes. Car washes use high pressure sprays to clean the car's undercarriage and prevent rust. That said, not all car washes are equal, and some tend to clean car undercarriages better than others.
What's undercarriage damage on a vehicle?
This is when the underside of the vehicle is damaged. It includes damages to the frame, body or axles, along with the fittings.
How do I clean the undercarriage of my car?
You can pressure wash the undercarriage of your vehicle using diluted detergent. Also, never pressure wash your car near or on gravel. Always, choose a smooth surface to avoid stones bouncing off the ground and ruining the paint of your vehicle.
What is the undercarriage of a car called?
The undercarriage of a vehicle is the part that is underneath the main body of the car. While the term was derived for horse-drawn carriages, its usage has broadened to vehicles and even to describe aircraft landing gear.