Hi. My S is now my daily driver and I'll be driving in lots of rain and any other condition that I can't avoid. I can keep the outside of my car clean but what about the underside where all the dirt gets splashed? Can this affect the car's performance? Do you clean the underside of your cars? If so, how? Does one even need to worry about this?

 

No. If your gung ho, you can get underneath your car in the spring time and clean by hand with soap and water.

 

It's really only important to clean the under carriage if you live in an area where road salt is used.

 

i pretty much just clean what i can reach (unless i am doing a wheel cleaning too)... i do know guys who put their car up on hydraulic lifts to clean under it-

but even for shows all you usually need to do is to get what you can reach (take off the wheels and wash and detail the wheel wells, brakes, etc. as well as both sides of the wheels). i then use a spray type wax in the wheel well area when it is clean before putting the wheels back on.

for most "normal" folks, no undercarriage work is really needed unless you are concerned about salts from snow covered roads (as mikeyc mentioned) or sea salts (possibly a slight concern for you). if you live near the beach, you might spray off the underside once or twice a year... drive the car a couple miles to dry that part off after. again, not a big deal.

 

Living in NYC, I like to thoroughly clean my undercarriage at LEAST once a year. I usually do it in May, when all the salt and crap is off the road. Put the car on jackstands, and go to town. When Im done, you can eat off the bottom of my car. Even now, 3.5 years later, the bottom of my car looks brand new.