The average MPG for a 1999 Ford Ranger 4-cylinder 5-speed manual transmission varies depending on several factors including driving habits, vehicle condition, and terrain. However, a reasonable estimate for combined city and highway driving would be
between 18 and 22 mpg. You might see slightly higher highway MPG and lower city MPG.
To find a more precise figure, you could consult the owner's manual for the specific vehicle or check online resources like the EPA's FuelEconomy.gov website (though older vehicle data might be limited).