Due to the way that power is delivered in an EV, the lack of a regular gearbox, and the non-linear nature of air resistance, EVs have ranges that increase the slower you go. At 20mph the range of a Tesla damn near doubles by some estimates. This is the opposite of how ICE cars work, which typically get better MPG at higher speeds due to gearbox design and variable efficiency based on engine RPM.

That’s probably why milk floats could go so far at the time despite obviously inferior battery technology; milk floats didn’t go very fast.