the 4 suspension areas and the wheel wells, i can somewhat clean them with a brush & running water. but how do i get all the sand & crap off the undercarriage?? do drive-through car-washes effectively clean the undercarriage?

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Current cars:
2001 MB E55 AMG
2003 Honda S2000
2000 Honda CRV

Gone but not forgotten:
2004 BMW 325i 5sp sport
1999 BMW 540i sport
1997 MB E420
1995 BMW M3 coupe

Steam cleaner works wonders. Sometimes costco has cheap electric units.

Pressure wash for a real cleaning, Karcher makes a bent wand/nozzle for this.

For maintenance purposes put your lawn sprinkler under it for a few minutes and relocate it 3-4 times. This helps to remove some salt.

When washing the fenderwells put some time into the wheel arch lip front and rear, we try to wash that area every time.

The only effective way I've found was to lift up the car on all four jackstands, remove the tires and scrub away!

I usually find a way to do other servicing if I have to remove wheels (shocks, brakes, etc.).

With the wheels off, it's a good time to remove the brake dust and crap from the inner wheel rims.

This weekend I was painting calipers on the ML, so I finished off the job with an undercarriage scrubdown!

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car