Web server MPG different from aCar app MPG

[janekgti]

I have the following recorded via the app:
ODO Gallons trip accu gallons MPG
start 11610
partial 11800 5 190 190 5
partial 12300 5 500 690 10
partial 12350 2.6 50 740 12.6
full 12462 3.5 112 852 16.1 52.91925466

The app calculates the MPG correctly: 52.92 MPG.
But the web server calculates 21.86 MPG even though it has the same records.

UPDATE:
The web has corrected its calculated value and it is now in sync with the app.