Move people, not labels

Compare walking, cycling, public transport, electric cars, combustion and hydrogen per useful trip.

The comparison starts with a person and a destination

The vehicle is not the service: the service is moving someone

It is easy to fall into the mistake of comparing vehicles against each other as if they were the object that matters, when the service that actually matters is moving a specific person or a specific good from a specific origin to a specific destination. An electric car eliminates the exhaust pipe and usually converts stored energy into motion more efficiently than an internal combustion engine, but it still incorporates a battery that had to be manufactured from minerals extracted and processed somewhere, still takes up the same space on a congested road, still wears down tires that release particles as they roll, and still needs the same road infrastructure as any other vehicle. A hydrogen car adds, to that same equation, the entire additional process of producing the hydrogen and distributing it to the refuelling point. And a bus running practically empty is not automatically more efficient than a well-occupied car, however it may look at first glance: a collective transport mode's real efficiency depends critically on its actual occupancy rate, not just its theoretical design.

The variables that actually decide the outcome

The final result of comparing two transport options depends on a wide set of variables that are rarely all mentioned together: the energy and material cost of manufacturing the vehicle itself, its size and weight, how many people or how much cargo it actually carries on each trip, the distance traveled, whether the energy it consumes comes from electricity, a fossil fuel or hydrogen, the efficiency with which it converts that energy into useful motion, and the total service life during which that vehicle will operate before being retired. Swapping an internal-combustion SUV for an equally large and heavy electric SUV can improve the vehicle's direct emissions while driving, but can simultaneously worsen the total amount of materials extracted and processed to build it, especially because of the size of battery needed to move that much mass. Directly avoiding an unnecessary trip, or sharing the same journey among several people, changes the need for transport at its very origin, even before considering which specific vehicle to use.

Walking and cycling are not free, but they are extraordinarily efficient

Moving on foot or by bicycle requires real metabolic energy, which in turn comes from the food consumed, and that food carries its own energy and environmental footprint of production. But even accounting for this, walking and cycling remain, by an enormous margin, the modes of travel with the lowest energy consumption per person and kilometer traveled of all available options, far below any motorized vehicle, including the most efficient collective transport. Their practical limitation is not energy but distance and available time: they are extraordinarily efficient options for short and moderate trips, but they do not replace a motorized vehicle for a long distance, nor do they meet the needs of people with a disability that makes this kind of travel difficult.

A hierarchy, not a religion

When feasible, in this order: avoid unnecessary trips; walk or cycle; use well-occupied collective transport; share a journey with other people; and choose the smallest, lightest vehicle that actually meets the service needed. Electrifying what remains reduces fossil fuel consumption and local pollution, especially where the grid's electricity comes largely from low-carbon sources.

For long trips, high urban density with no reasonable collective alternative, disability, freight transport or emergencies, this hierarchy changes and is not always literally applicable. A just transition offers real alternatives before penalizing those who do not yet have them available.

Don't confuse the vehicle with the solution

A large, heavy electric car can still be, in total material terms, a worse option than a small, well-occupied combustion car; a vehicle's size and real occupancy carry as much weight as its energy source.

The numbers, with their source

Walking and cycling, in a league of their own

Comparing energy consumed per person and kilometer traveled, walking consumes on the order of 0.16 megajoules per passenger-kilometer and cycling around 0.06 megajoules per passenger-kilometer — cycling turns out, in fact, to be more efficient than walking. Among motorized options, tram or light rail consumes around 0.91 MJ/pkm, the bus 0.92 MJ/pkm, heavy rail or conventional metro around 1.65-1.69 MJ/pkm, motorcycles 1.73 MJ/pkm, and cars 2.10 MJ/pkm — meaning a car consumes roughly 2.4 times more energy per passenger-kilometer than a bus, though that comparison depends critically on each vehicle's real occupancy on each specific trip.

Source: transport-mode energy consumption comparison collected at c21.phas.ubc.ca (Energy Cost of Transport) and in comparative studies of public transit versus private vehicles.

An electric car "breaks even" with a combustion car after a few years of use

Globally, a medium-size battery electric car generates, over 15 years and around 200,000 km of use, roughly half the total lifecycle emissions of an equivalent internal-combustion vehicle. The breakeven point — the mileage from which the electric vehicle has already "paid off" the excess emissions from manufacturing its battery and starts emitting less in total than the combustion vehicle — varies a lot depending on a country's electricity mix: in the United States it is reached at around 41,000 km (roughly two years of typical use), while in China, whose grid is still heavily dependent on fossil fuels, that breakeven point is not reached until around 118,000 km (roughly ten years).

Sources: IEA — Global EV Outlook 2024, Outlook for emissions reductions; comparative analyses from BloombergNEF and ICCT on electric vehicle emissions breakeven points.

What this table is missing

No energy-efficiency or emissions-breakeven figure replaces the variable that matters most in practice: how many people actually travel in that specific vehicle on that specific trip. A small car with four occupants can outperform a half-empty bus in efficiency per person, and vice versa.

Sources

• The IEA analyses lifecycle and battery impacts in Global EV Outlook.
• The European Environment Agency compares electric vehicle impacts.
• The IPCC highlights the combination of urban planning, active transport, collective transport and electrification in Transport.
• The International Council on Clean Transportation (ICCT) publishes comparative lifecycle-emissions analyses between electric and combustion vehicles.