Just did a ride on my ST3 around Monmouth shire and Gloucestershire. Stopped for fuel as my warning light had been on for a while and just about to join M48. It took 17.1 litres and the trip said 200 miles. If I did that mileage on the ST2, it would probably take about 20 litres.
Personally I think the handlebars are swept back too far, handlebar conversions works nicely. ST4 Had 200 miles from a tank running on vapours could only get 19 litres in. An old fuel filter will dull the performance . Buy yourself a torque wench