The EPA estimated fuel economy for a 2003 Chevy Suburban varied considerably depending on the engine. There were several engine options available that year. You won't find a single MPG figure. To get an accurate MPG, you'll need to know the specific engine size (e.g., 4.8L, 5.3L, 6.0L, or 8.1L).
You'll find the most accurate information on the sticker inside the driver's side doorjamb of the vehicle itself or in the owner's manual if you have it. Online resources may give ranges, but those will be broad estimates.
