The Green Prize offers a maximum of $50,000. To win the Green Prize in the PAV Challenge, the competing aircraft must score the highest MPGe, or equivalent miles per gallon. MPGe is the vehicle's mileage based upon fuel price, fuel density and the payload carried. A series of tables are given in the rules that delineate how this scoring works. MPGe is evaluated after the aircraft flies the CAFE 400 race course.

The floor of the prize winning starts at 30 MPGe for a 2 seat aircraft carrying 400 pounds of payload during its CAFE 400 race. The winning aircraft must also average at least 100 statute mph during the race, including allowance for its GTT or ground travel time. The GTT strongly determines the DtD speed in the CAFE 400 race. GTT respects the time required to park the aircraft and then walk, bike or drive to and from the destination doorstep. GTT is proportioned according to the aircraft's takeoff distance, and is shortest for those with the ability to takeoff vertically (VTOL). Long takeoff distances imply using long runway airports that are usually farther from town and require longer GTTs to reach the destination doorway.

The prices for fuels and electricity in the Green Prize have been carefully selected from national averages. They reflect some subsidy for bio-fuel as well as a slight premium for obtaining mogas at an airport location. All fuels must be approved and inspected by CAFE.

Each aircraft competing in the Green Prize will be carefully weighed on the CAFE scales before and after its CAFE 400 race flight in order to determine its fuel burn. The CAFE 400 race course is a VFR cross-country flight over beautiful Northern California that includes several climbs and descents, with some pylon check-points as high as 7000 feet MSL. Teams competing for the Green Prize must optimize every facet of their aircraft's cross-country performance—aerodynamic, thermodynamic, structural and propulsive efficiency, as well as navigational accuracy, use of wind, weather and upslope effect.