I think the Civic's relatively poor performance in both the comparisons might come down to the fact that neither loop started with a hot engine. The city route was "warm start", highway was "cold start".
I suspect the Civic's city numbers are pretty horrible [relatively speaking!
] until autostop is operating.
I was following the Civic, prepared to "manually auto stop" the Mirage's engine if I saw the Civic's stop. But on our way through the city to the freeway, and it never did stop (I could always see the tail pipe vibrating).