Car Wash Undercarriage Wash Question

February 24, 2017 2:38 PM

When you take your car through a typical gas station car wash, and select the undercarriage wash option, does the undercarriage spray last for a set time, or does it go on for as long as your car is over the spray jets? Whenever I get this done, I'm never sure if I should drive over the spray more slowly or more quickly, in order to get the most thorough wash.
posted by Enemy of Joy to Travel & Transportation (3 answers total)

Best answer: In all of the ones I've been at, it's both. It sprays for a set time or until your car clears the sensor, whichever happens first. I figured this out because I drive a manual and have sometimes snubbed it going so slow - the washer quits after like 30 seconds or however long.

In theory, I guess, you should go slowly. More cleaning is more cleaning. In practice, I never really have the patience and whenever I really need to clean out the underside, I go to one of those washit-yerself places.
posted by Pogo_Fuzzybutt at 2:47 PM on February 24, 2017 [1 favorite]

They're time limited, and newer units will actually display the timer so you know how slowly to drive.
posted by DaveP at 4:45 AM on February 25, 2017

On the other hand in most car washes I've been in parts of Europe you pull forward to a certain point, put car in neutral, turn off engine and car gets pulled through and any and all liquids, brushes and air only work as long as your car is able to benefit from it on its journey through the tunnel.
posted by koahiatamadl at 7:53 AM on February 25, 2017