Digital Fuel Gauge Accuracy?

I got a little freaked out when I filled my tank. Said 0km left but I managed to put in exactly 20 litres.

After I started the bike up the gas Gauge still read 0 and no indicator bars. Thought something was wrong. I rode for a whole and then it started slowly getting the indicators full. Is that normal? Still got to get used to all these new features. Previous bike showed full tank immediately after turning the key.
 
Can you clarify what you mean? Why would you want to that?
Its a bugger to get out and in without bending the float which will change the accuracy of the gauge reading. I remember when the Triumph dealer did mine the first time. I picked the bike up and when I took off the guage said it was just about empty. so I pulled over a couple blocks from the dealer and could not even fit one gallon into the tank. Back to the dealer I went it took them a few trys but they got the float bent back right so the reading was there. One big lesson I learned for when I did it myself. Others over the years have had the same problem when they went to change there filter.
 
Surely there is no need to be rough when they change the filter.
 

Yes, that's normal on the newer ones.

Mine's the same way.
 

Mine does this too.

Turns out my refuel light pops on with 2 gallons left in the tank rather than the 1.2 the manual said it would.
 
as warp says it all has to do with the state of your float.

on my 2010 roadster the light comes on when there's 4 bars left on the gauge, which is always at 40-42 miles left when in town and 60-62 when out on open road.
if i fill up at that point it takes 16 litres exactly, so i figure with a 24 litre tank that means the light comes on when there's a 3rd of a tank left.

the best i've seen after filling up is 240 miles, and this was with the carpenter 240 kit. before that the best i remember was 225 miles, butt then again i didnt have the bike only a few months before i fitted the carpenter bits.