Ford 1997 Crown Victoria Manual page 243

To calculate fuel economy:
1. Fill the fuel tank completely and record the
initial odometer reading.
2. Every time you buy fuel, record the
amount (in gallons or liters) purchased.
3. After at least 3-5 tankfuls, fill the fuel tank
and record the final odometer reading.
4. Use these equations to calculate your fuel
economy:
English: MPG = (total miles driven)
(gallons used)
Metric: L/100k = (liters used)
(100 kilometers)
Comparisons With EPA Estimates
EPA fuel economy figures are obtained from
laboratory tests under simulated road conditions
and may not reflect the actual conditions you
experience or your style of driving. The EPA
fuel economy estimate is not a guarantee that
you will achieve the fuel economy shown.
The following decrease fuel economy:
Lack of regular, scheduled maintenance
Rapid acceleration and excessive speed
Driving with your foot on the brake
Sudden stops
Extended engine idling
Using speed control in hilly terrain
Extended use of the A/C, defroster, rear
window defroster and other accessories
Underinflated tires
243