Upgrades are not only influenced by elite status, but certainly also by fare paid. When I used to travel quite a lot of short haul in Europe at full fare economy, I had a 95% success rate getting upgraded to C - also when economy was not full. Was RW at the time. At the moment - being PE - I rarely get upgraded when travelling on deeply discounted tickets. Got lucky last Friady on LHR-AMS...but that is a rare occasion these days.