R Class Fuel Capacity

[manwagon]

The Specs for the R Class list a 21.1 Gallon Fuel Tank with a 3.4 Gallon Reserve. I wish this meant a fuel tank size of 24.5 Gallons but I think it means the "Low Fuel" light comes on with 3.4 gallons remaining in the 21.1 Gallon tank.

Is that correct?

Also, why does the R Class have 4 gallons less fuel capacity than the 25 Gallon capacity of the ML when they are both built on the same frame?

[BobbyHowie]

Our R350 has a 80L tank including a 13L reserve which is around 17.5 UK gallons including a 2.8 UK gallon reserve.