Miles Per Dollar Calculator is a Firefox addon, can calculate the estimated price for gas for the distance in miles selected on a page. MPG and gas price are set in the add-on Preferences.
When you select (highlight) with mouse distance to drive (ex: "490 mi" or "490"), the add-on will calculates price for gas and show it in the popup message. You specify average MPG of your car (ex: 30) and average gas price (ex: 3.99) in Preferences.

Requirements:
* Firefox

The license of this software is Freeware, you can free download and free use this browser plug-ins software.