1993 Cadillac DeVille Owner's Manual - Page 144

Your Fuel Data Center has five buttons. Here's what they do: INST (Instantaneous Fuel Economy), Push this and you'll see what your fuel economy is at that instant. The computer takes a new reading twice every second. It will show economy up to 70 miles per gallon (or, in metric, 2 litres per 100 kilometers). AVG (Average Fuel Economy), I - This reading is your average fuel economy since the last time you reset the system. "Avg" shows total distance divided by the total fuel used.