Physics: Why EVs Waste Less Energy Than Petrol Cars

Energy cannot be created or destroyed, only converted from one form to another — and every conversion leaves some energy behind, usually as heat or sound. Efficiency measures how much of the input energy ends up doing something useful, often expressed as efficiency = useful output energy ÷ total input energy. In transport, this single ratio separates electric cars from internal combustion engine (ICE) vehicles: batteries deliver a far greater share of their stored energy to the wheels, while petrol and diesel engines lose much of theirs as waste heat and noise. That gap matters far beyond the physics classroom. Because less energy is wasted, electric vehicles need less total energy to cover the same distance, which lowers demand for fossil fuels and the emissions and air pollution that come with burning them. Efficiency, in other words, connects a simple energy balance to cleaner air, better public health and more sustainable transport.