The region they did this flight in charges ~$.25/kw. So they would have had to do the entire flight with 20kw/h or an average of 40kw of output. That’s 60hp, or about a third what your Cesnna uses on climbout. Even if you give them a very low price of $.10/kw then they are flying with less than the Cessna on climbout. Hell, a Cessna in level flight uses ~80 kw.
In other words, they are claiming that they can fly this thing on a VW beetle engine, or the PR guy got the number wrong.
A Dornier 328 (roughly similar in size) has two 1625 kW engines. Heart stated they "delivered more than one megawatt of power" during the flight, so maybe comparable to one of the Dornier's engines at 60% power? Even the DC-3 could take off with one engine but 60% seems iffy.
At 1000 kW and $0.10/kWh (being very generous I think), the plane would be using $100/h (at 1000 kW level) or $1.67/minute. You'd blow past $5 in 3 minutes.
I don't like that they don't share the basic numbers. It's as if they don't want folks doing the math.
I use Mogas in my plane and even that is painful these days