I actually did this test today on my new to me 2013 Sportster 72 with the 2.1 tank.

In relatively easy highway cruising at 80-120 km/h (50 -75 MPH), the light came on right at about the 100 km (60 miles) mark.

To fill at this stage required about 5 liters.

So, since the tank does hold around eight liters, the claims of 160 kilo's (100 miles) per tank does seem to hold true... At least for me, and my riding style.

 

The tank size accommodates the range of 99% of my rides. The only thing I was initially skeptical about was road trips. Let's say you fill up, and then come upon a fuel stop 45 miles later. You've been in the saddle less than an hour, so you don't want to stop.Can you risk passing it up. What if the next stop is 60 miles away. You could be pushing the bike. I bring a fuel can with on long trips. Never used it, but came into a few stops sputtering.

 

Daily commute at 60-70 mph (mostly highway and freeway riding) for 60 miles round trip I put in 1.25-1.4 gallons when I fill up (the difference is in how I control the throttle). I average around 44-45 mpg with that type of riding. Again, depends on how aggressive you are with riding and how much stop/go you have. I myself will not push it past 75 miles without a fill up.

 

My fuel light comes on around 63 miles. I usually go another 20 before I fuel.

 

Having only owned my bike for a couple weeks and mostly to and from work , I got a chance to take a leisurely cruise to the boonies.
I went 71 miles on 1.43 gallons which calculates at 49.65 MPG.
I never ran over 60 MPH on this trip.
My light usually comes on between 59-69 miles around town , but the mileage generally goes 40-42 MPG.
This is bone stock so far.
Mick

 

I get the most horrendous gas mileage. In the city I get around 30 mpg. 35 is about my average when touring. I'd never let the tank go dry so i'd probably be filling up every 50 miles.

 

Holy crap thats a new record. I am luck to get 70 mpg

 

My light comes on at 62 miles and I've never pushed it past 75. When I did that, I put in 1.8 gallons.

 

It was a long (750 mile) backroads trip. Was averaging 48-53 MPG depending how twisty the road was . I ran out right at 110 miles.

 

Old thread revival! Got gas for the first time in my 48 today went 70 miles and got 1.6 gallons of gas. Fuel light did not come on not sure if that is working or not. It had the digital HD tachometer / speedo.

Will try to take it to 80 and see if the light comes on. Figure I can hit 90 to 100 on a tank.