On a LA to NY trip of 2100nm, the Tecnam will burn $825 in Avgas, or $525 (this is airline competitive prices) in Mogas
With how many stops? 4 minimum, with all seats full 7? Obviously flying in the US is more reasonable but 7 stops in Europe starts to stack up. Especially if one has to utilise proper airports, which on a long international flight one would have to to be assured of completing the mission. Providing icing isn't an issue. Also the 2100 nm will take a looooong time.
The right avgas burner should be around 20-24 gph. Anymore than that would be discounted in my search for cost reasons.