Yeah, but it's
so frickin amazing, it leaves me more than a little skeptical. Especially after seeing the numbers from the Mirage you tested.
Their 75 mpg US (31.9 km/L) from a target speed of "80-90 km per hour" doesn't sync with the numbers you saw in your test car of ~58 mpg US / ~24.5 km/L at 80 kph / 50 mph.
Sure, their trip average speed would have been lower than their target cruising speed. And sure, their cars were different than yours (they had better aero, significantly higher tire pressure).
O wait...
I just took a look at topographical info for their route, and guess what: they went from sea level, to ~2000 ft / 609 m and back again. One giant pulse & glide?
Or many pulses and glides, perhaps even with some neutral coasting on the way back down to Bangkok?
The needle on the plausibility-o-meter just jumped a little higher.