Reduces NOx by reducing combustion temperatures.

The newest MB engines don't use EGR.

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How do they handle the NOx ?

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
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NOX is produced under hot combustion (inner-cylinder) temp. Exhaust gas, considered inert, when directed into the intake actually lowers the overall combustion burn temp. Therefore less NOX at the tailpipe.

The EGR valve opens when a control solenoid is energized. The conditions are when the engine is not idling or at wide open throttle. The check engine light will come on after several attempts monitoring the EGR function and it detects errors.

The computer requests EGR and fires the solenoid. Vacuum opens the valve and exhaust flows into the intake. The RPM should drop slightly when this occurs. No RPM drop - flag failure.

You could roll with it plugged or blank the EGR off but increased combustion temp. over an extended period may introduce problems. Mine seems to run as well in or out of circuit. I've have it in because I wanted to retain the Check Engine Light function. You'll either have to reset it constantly or pull the bulb. There's no way to trick the computer into thinking EGR is working.

My guess is they use a variable exhaust cam, like some other engines use.

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95 E320 Cabriolet, 169K