Is there any consensus as to how much driving in a good rain really washes out the undercarriage? Having a semi-stupid argument with a know-it-all neighbor.
I'm saying: If you live anywhere that the roads are salt/brine treated in winter you're foolish not to give everything you can reach under there a good rinse come spring.
He's saying: That's BS, all you need to do is go for a drive in a heavy spring rain or two.
I can see that his approach is better than not doing anything, and that it probably does help a little. But that it's no substitute for a serious rinse with the hose.