* 2.0L Zetec 4-cylinder: This was a popular choice.
* 2.3L Duratec 4-cylinder: A larger, more powerful option.
There may have been variations within those engine sizes as well, based on specific model year and configuration. To know the exact engine size for a specific 2005 Ford Focus, you'd need to check the vehicle's identification number (VIN) or the vehicle's documentation.