Found one very good thread.

Changing EZL reference resistor to alter ignition mapping on a W126

I noticed that if I use 92 or 95 octane, I get less fuel mileage with the resistor in S.

With 98 octane, I get to 400+km before the low fuel light lights up.

I wonder what's the logic, would it mean that with the resistor in position 2 (for 95 octane), if I use 95 octane fuel, I would get the same performance as using 98 with the resistor in S?Albeit lower fuel costs?

Hmmm.....