No. the last trip was not a full 15.8 miles commute but a special trip in the morning to get gas that would be exactly 12 miles because I already had 788 miles logged by then. The previous day I got 73 mpg combine/68 mpg uphill and 78 mpg downhill on the scangaugeII. After filling up with gas -- starting from a warm engine at the gas station and going downhill to work for an additional 10 miles the ScangaugeII said I got 92 mpg (prewarmed up engines are more fuel efficient). So you might want to average out 92 and 66 mpg --> 79 mpg downhill for 22 miles.