> Shifting to cruise control did not affect the drainage curve at all, and when he called Tesla they suggested that cruise control was a Bad Idea, because the Tesla has regenerative braking, so you see that he turns it off at about 225 mi and starts stop-and-go driving in the city.

Braking and cruise control are mutually exclusive domains. You can't drive with cruise control in stop-and-go traffic even if you wanted to.

Turning off cruise control on the highway might have some small impact on efficiency, but the cause would not be braking.