If you do the math, the 7.9
If you do the math, the 7.9 kWh Zero S ZF9 gets 43 miles of highway range, which works out to 184 watt-hours used per mile. The 9.3 kWh Empulse R gets 56 miles of highway range, which works out to 166 watt-hours used per mile, or about 10% lower energy consumption than the Zero.
Scuttlebutt is that the R has a fairing, which should help highway range. So it's unclear how much of the improved highway range is due to the transmission and how much is due to the fairing. We'll see on May 8 if the fairing rumor is correct.