tank range on X country

I only get 80-85 miles before the light comes on, mostly town riding, seems low to me, what do you get?

I'd say do the maths yourself.

Brim your tank, zero the trip, brim again after 80 miles or so and work out how many miles per litre you've been getting - Then multiply by the officail tank capacity and there you have your tank range based on your type of ridding.

When the light comes is not really relevent to tank range it's a common point of refference between full and empty.