I guesstimate that you normally get 50 miles out of "reserve".

Yellow light comes on in my 1.6 focus at 50miles left to empty. I've done another 4 miles on 0 miles remaining tucked in behind a lorry doing 55mph, it cut out on the forecourt.

On the bike I've done 42 miles on "flashy bar" and that was down to necessity. Wouldn't like to take it much further.