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Why an electric motor beats an engine — in physics, not vibes

Two questions decide whether electric is really better: how much of its energy reaches the wheels, and how much carbon it emits once you count the power plant. Set the numbers and see both — for any grid, including a dirty one.

Electricity source

Energy that reaches the wheels

3.8× more of its energy an EV puts on the road
Fossil engine21%
Electric (grid → wheel)79%

CO₂ per km, well-to-wheel

Fossil car208 g/km
Electric car110 g/km

Even on a Bangladesh grid, the EV emits 47% less CO₂ than petrol — well-to-wheel.

How this works

An engine is a heat machine: most of the energy in petrol leaves as heat through the exhaust and radiator, so only about 16–25% ever turns the wheels. An electric motor wastes almost nothing — roughly 85–90% of the energy in the battery becomes motion. Even after charging and grid losses, an EV puts around three to four times as much of its energy on the road.

On carbon, the trick is that a power station burns fuel far more efficiently than a tiny car engine. So even when electricity comes from gas or coal, the EV's huge drivetrain advantage usually keeps its well-to-wheel CO₂ below a petrol car's. Clean the grid up and the gap becomes enormous.

Figures: ICE tank-to-wheel ~16–25% and EV battery-to-wheel ~85–91% (US DOE); petrol 2.31 kgCO₂/L plus ~20% upstream; grid factors from IEA / Bangladesh DoE. Estimates for illustration, not a lifecycle assessment.