We had a 500 earlier this year with the c-18 engine , thing only burnt about seventeen gallons an hour and would sit at the 130kt vne all day
good heli , very stable , easy to fly but keep an eye on the auto's, once you hit the ground dont be tempted to pull back the stick as you will chop your tail off!
also watch out for landing on long grass especially on low skids or it will BBQ time,
fun heli
enjoy!