Ugh,
that top chart is a disaster, especially the last row at 6000 m
445 IAS is 610 TAS ( 330 knots )TAS, not 515 ( I highly doubt 67 km/h instrument error ). Even then, I get 4.1 mpg, not 5.0.
The other 3 rows look reasonable, except the IAS in the first row should be right around 300. Although, I suppose there could be 25 km/h instrument error? Seems like a lot