The second link given on a Google search for "Breguet Equation" is to a PDF document from MIT. On page 7 of this document is a chart showing L/D ratios for various commercial aircraft (turboprop, regional jet, and "large aircraft") plotted against the year the aircraft entered service. Below is an image of this chart:
What appears to stand out (at the top of the chart) is the Fokker F28 aircraft.
From an engineering and operational perspective, what enabled that aircraft to have such a high L/D ratio?