How EV Speed-Efficiency Calculations Work
Electric vehicles are highly sensitive to highway speed. Aerodynamic drag — the primary resistance force at speed — increases with the square of velocity. Going from 65 to 80 mph increases drag by roughly 51%, directly draining the battery faster.
The efficiency multipliers used here: 50 mph +20%, 55 mph +12%, 65 mph baseline, 70 mph -8%, 75 mph -15%, 80 mph -23%, 85 mph -30%. These are average estimates; your car's actual aerodynamics will vary.
Frequently Asked Questions
Does cold weather affect range at highway speeds?
Yes. Cold temperatures reduce battery output by 10–30% on top of aerodynamic losses. Preconditioning the battery while plugged in helps reduce this impact.
Does regenerative braking help on the highway?
Minimal benefit — regen is most effective in stop-and-go traffic. On open highways with consistent speed, aerodynamic loss dominates.