* Engine size: The 1999 Suburban came with a few different engine options (5.7L, 6.5L diesel, and 7.4L). The larger the engine, the lower the fuel economy.
* Transmission: Automatic transmissions generally have slightly lower fuel economy than manual transmissions (though a 1999 Suburban is almost certainly automatic).
* Driving conditions: City driving yields significantly lower MPG than highway driving. Terrain (hills, mountains) also impacts fuel economy.
* Vehicle condition: Proper maintenance (tire pressure, tune-ups, etc.) affects gas mileage. A poorly maintained vehicle will get worse gas mileage.
* Driving style: Aggressive acceleration and braking significantly reduce fuel economy.
General Expectations: Expect relatively poor fuel economy from a 1999 Suburban, regardless of the engine. You're likely looking at:
* City driving: 8-12 MPG (miles per gallon) is a reasonable range, potentially lower depending on the engine size and conditions.
* Highway driving: 12-16 MPG is a reasonable range, again potentially lower.
To get a more precise estimate, you should specify the engine size and look up fuel economy data specifically for that configuration. You can try searching online using the exact engine size (e.g., "1999 Chevrolet Suburban 5.7L MPG") or checking resources like the EPA's FuelEconomy.gov website (though older vehicle data might be limited there).
