You'll find a wide range of reported MPG, from a low of around 10 mpg for heavy-duty models with large V8 engines to a high of perhaps 18 mpg (or slightly higher) for lighter models with smaller engines and careful driving. Most likely, it would fall somewhere in the 12-16 mpg range.
To get a more accurate estimate for a specific 1992 Chevy Silverado, you'd need to know its engine size and transmission. You can often find this information on the vehicle's sticker or in the owner's manual. Even then, individual driving habits will heavily influence real-world fuel consumption.
