For the level of significance, yes. The speed component of energy consumption is huge at highway speeds, but moderate at 30mph, because of the growth rate of air resistance with respect to speed. The relatively smaller contribution at lower speeds means that losses due to gearing can negate most of the benefit.
This is because while the vehicle is going slower and so incurring lower resistive losses, in an ICE car you’ll be in a lower gear, so the engine will be turning over at a similar speed, or perhaps even higher, incurring similar or higher resistive losses. These losses are a greater relative component of the total energy consumption at low speed than at high speed. (And at high speed you will not need to gear down when reducing your speed, so decreased speed will pretty much always result in a proportionally lower engine speed)
For the level of significance, yes. The speed component of energy consumption is huge at highway speeds, but moderate at 30mph, because of the growth rate of air resistance with respect to speed. The relatively smaller contribution at lower speeds means that losses due to gearing can negate most of the benefit.
This is because while the vehicle is going slower and so incurring lower resistive losses, in an ICE car you’ll be in a lower gear, so the engine will be turning over at a similar speed, or perhaps even higher, incurring similar or higher resistive losses. These losses are a greater relative component of the total energy consumption at low speed than at high speed. (And at high speed you will not need to gear down when reducing your speed, so decreased speed will pretty much always result in a proportionally lower engine speed)