* Engine size: The larger the engine, the lower the MPG.
* Transmission: Automatic transmissions generally get slightly worse fuel economy than manuals.
* Terrain: Off-road driving drastically reduces fuel efficiency.
* Driving style: Aggressive acceleration and high speeds will lower MPG.
* Vehicle condition: Proper maintenance and tune-ups can help improve fuel economy, but only to a limited extent.
Expect the lower end of that range (8 mpg) or even less under less-than-ideal conditions. You should not expect to achieve the higher end of that range consistently.