Englishal, I accept that new aircraft are better but the vast majority of light aircraft being used now are most certainly not new. Can there surely not be a postmod available to refit these aircraft ?
You also mention GPS which is I suppose is something, it is however totally dependent on what you type in and it can only calculate from what you have told it. Aircraft with 2 or 3 FMS's have still run out of fuel eg Gimini Glider, Hapag Airbus etc.