I do not know about MBZ cluster and it would be hard to believe the ODO does not register mileage if the cluster shows speed correctly.

All modern cars use 'drive-by-wire' technology. A sensor in the drive axle generates pulses which is fed to the on-board computer to calculate speed and distance travel. If the car registers speed correctly ( the pulse is converted to an analogue signal to drive the speedo ) then the ODO should go up as expected. The ODO reading is only a counter in the car's computer. Removing the battery has no effect as the counter is stored in non-volatile ram or flash, similar to USB drive.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.