Fuel purchase planning along a route

1. A method executed by a mobile device including a GPS-enabled navigation program, comprising:

obtaining a fuel tank size, amount of fuel in the tank, and a fuel efficiency for an automobile;

accepting user entry of a destination for traveling in the automobile;

automatically identifying a current location and determining a route to the destination;

acquiring, for each of a plurality of refueling stations along the route, a location of the refueling station and a current fuel price being offered at the refueling station;

providing output recommending one or more refueling stations at which to stop and a quantity of fuel to purchase at each of the one or more refueling stations in order to reach the destination without running out of fuel and minimizing the price of fuel purchased; and

displaying a route to the recommended refueling stations.

2. The method of claim 1 , further comprising:

accepting user entry of a target duration for traveling from the current location to the destination; and

determining a number of refueling station stops that may be accommodated without exceeding the target duration.

3. The method of claim 2 , further comprising:

accepting user entry of an acceptable savings per unit of time delay, wherein the recommended refueling stations may include an off-route refueling station so long as the amount of money saved by purchasing fuel at the off-route refueling station exceeds the value of the delay in reaching the off-route refueling station, wherein the value of the delay is determined by the product of the time delay reaching the off-route refueling station and the user-entered acceptable savings per unit of time delay.

4. The method of claim 2 , further comprising:

determining a total travel time based on the speed limits for each section of the route;

subtracting the total travel time from the target duration to determine the amount of time available for stopping at the one or more refueling stations, wherein determining a number of refueling station stops that may be accommodated includes dividing the amount of time available for stopping by a user-entered time delay per refueling station.

5. The method of claim 1 , further comprising:

accepting user entry of a minimum acceptable fuel purchase, wherein the recommended quantity of fuel to purchase at each of the one or more refueling stations is not less than the user-entered minimum acceptable fuel purchase.

6. The method of claim 1 , further comprising:

calculating a net change in elevation between the current location and the destination; and

adjusting the fuel efficiency to account for the net change in elevation.

7. The method of claim 1 , further comprising:

accepting user entry of a minimum refueling station quality;

identifying a refueling station quality rating for each refueling station; and

recommending only refueling stations having at least the minimum refueling station quality.

8. The method of claim 1 , further comprising:

determining and displaying an estimated total cost of fuel to reach the destination by purchasing the recommended quantity of fuel at the recommended refueling stations.

9. The method of claim 8 , further comprising:

determining and displaying an estimated total cost of fuel to reach the destination by purchasing fuel at an average price of all refueling stations along the route.

10. The method of claim 1 , wherein the recommended quantity of fuel to purchase is identified by the total cost, volume of fuel, or percentage of the tank volume.

11. The method of claim 1 , wherein the estimated fuel efficiency is based on historical measurements for the automobile.

12. The method of claim 1 , further comprising:

accepting user entry of a preference whether or not to arrive at the destination with a given amount of fuel remaining in the tank.

13. The method of claim 1 , further comprising:

accepting user entry of an estimated time delay per refueling station.

14. The method of claim 1 , further comprising:

dynamically adjusting the recommended one or more refueling stations or recommended quantity of fuel to purchase at each refueling station in response to an updated location of the vehicle, an updated duration, an alternative fuel purchase, or a missed turn.