To give you some idea, on a flight earlier this month from DTW
on a 757, our pilot told us how much fuel we would be burning. I don't remember how many pounds he said, but I do remember that he also said it would be enough to power a minivan or SUV
for 8 years.
So my guess is that an Insight would get better mileage than a 747.
But compare how long it would take to get from DTW
in a 757 or 747 versus an Insight, and I think it's worth it.
David / HNL