Why does fuel economy get better on the highway, but EV range gets worse?
In: 463
Electric motors are approximately as efficient across their operating range, regardless of engine speed. Electric motors can provide maximum torque from zero RPM. But as you go faster, mechanical friction, rolling resistance and aerodynamic drag all increase, taking a bigger bite out an EV’s stored reserves.
Internal combustion engines (ICEs), on the other hand, must be designed and tuned to run efficiently at a specific engine speed. They are markedly LESS efficient overall the further you get away from this optimized RPM. ICE vehicles make very little torque at idle speeds, and waste a lot of fuel getting up to their operational “sweet spot”, where they make power most efficiently.
In stop-and-go driving, ICE vehicles must constantly transition through these inefficient lower engine speeds. Even though friction and drag losses increase at highway speeds for ICE vehicles just like they do for electric vehicles, they are less evident because the engine remains in that range of optimum designed efficiency.
Latest Answers