Except that she was never "on the road to Utah". Her destination was always Mesa, AZ. The only reason she continued on to Utah, was to use Ryan Burns as her alibi as to where she was when the murder happened. She claimed she was never in Arizona, that's the whole reason for the gas cans- to not have a paper/camera trail at Arizona gas stations, the inconspicuous rental car, and dying her hair brunette, not to mention switching license plates. She bought gas in every other state she traveled through but Arizona, that's why the 3rd can, so she could have enough gas not to have to stop.