Simply. NO!!
Not everyone has access to a 2-post lift, but why is washing the underside of your vehicle important?
These photos were taken of a 3 year old VW Armarok, the muddiest, dirtiest underside in the history of Rustbuster
Salt, Mud, Grease, Oil, Dirty Water, and Dust, typically road traffic film. But why is this a problem? Corrosion Rate Accelerators.
What are Corrosion Rate Accelerators? simply put anything that can increase the speed of corrosion setting into the metal on the underside of your vehicle. Anything that changes the pH of the underside of your vehicle will cause it to rust quicker, when in the presence of an electrolyte (moisture).
Now salt is obvious but what about mud? Soils and mud contain rich microbial communities and can include pathogens (including viruses, bacteria, and parasites) when in the right conditions (temperature, pH, oxygen and nutrient availability) will accelerate the corrosion of your precious metal.
So,
Chlor-X Salt Remover – https://www.rust.co.uk/product/cat/salt-removing-products/
Safer De-Greaser – https://www.rust.co.uk/product/safer-degreaser/
Both are pH neutral and can be applied at the same time.