Low fuel light comes on too early
 

I have a 2013 Mercedes Ml350 Bluetec and I have noticed that compared to the older 2010 Ml350 gas version I had before, the low fuel tank light comes on earlier. When I see the cruising range, I still have 60-80 miles showing on it when driving on highways. We do about 500 plus miles a week. When it gets filled up, the tank is around 20 gallons. The older one would put us at 22-23 gallons. The tank size is 24.6 gallons so its a bit early for the low light come on with so much left. Anyone chime in on this?

Too early? That's subjective. I think it's fine. My does come on with 5 gallons left, too.

Isn't it better to not let your tank get too low?

It is supposed to come on when you reach the reserve, which is about 12litres. I believe that is about 3 US gallons, which relates to 21.6 gallons. Whichever figure appears, the tank reading is not an exact science, I have known of greater variations.

The most important thing is to know your own tank, and ensure that reserve is never depleted!

The old ML350 light would come on with 3 gallons left and the new one will come on with 5 gallons left. Not sure why its earlier but I just get a bit irritated when I know I can do more miles on this bluetec with the cruising range capabilities. Its just a minor thing so I was curious if there was something wrong with my gas gauge.