Yellow light fever?!

My wife claims I have yellow light fever, because I like to drive around with my "lower fuel" warning light lit. For the record it is not true. My question though is, has anyone figured out, or knows, what the approximate range is on a 2003 Xterra once the fuel warning light comes on? I drove all the way home (to the gas station near my house) from work last week with it on, and my one way commute is 35KM's. My tank filled with 64.4 Litre's at the gas pump. I don't recall the total litre's for the Xterra, but I can tell you I drove 494.4 KM's on that tank of gas! (98% HWY at 110 KPH) The farthest yet! I usually get about 460 with my previous range high of 480 km.
Anyway, the low fuel light came on just as I was leaving work, so I now think that I have about 30-34 KM's range before running out.

Anyone else measured?

It's not good to run out of gas on fuel injected engines. Gas light warnings are pretty different on each truck. Sometimes mine comes on and I have lots of gas still. Other times it comes on and I've run out in minutes. :(