In the video, they did say that the C1 is the "most power-efficient modem ever in an iPhone." They also said that they have an "all new internal design for iPhone 16e that has been optimized for a larger battery."

Part of it is certainly the modem, but part of it is also likely to be the larger battery.

I'm really curious to see both how the Apple C1 performs and also how they changed up the internals for a larger battery and how much larger that battery is.