I'm having the same issue here. It seems to do the right calculations for me, but on the dashboard, some of the units are mixed up. Along the left side, it says L/100km and uses metric units. But along the bottom, it says MPG and uses miles.
I have not seen an update recently, per your responses above. Hoping a fix is still on the way - or sync is enabled in Gas Cubby so we can switch to that.