To drive 100 km, how much energy must actually be taken out of the ground?
Every link in the chain is adjustable. The Sankey diagram, the overall efficiency and the running cost are recomputed live. Default values reproduce the JEC Well-to-Wheels v5 figures.
By Robin Girard , MINES Paris — PSL. Bachelor course « energy and the low-carbon transition ».
Every figure is documented in the source repository , which also holds the code that reproduces this page. v1.0
Scenario
JEC vintage
2015 · NEDC
2025+ · WLTP
Powertrain
Primary-energy accounting convention
Physical energy content (IPCC AR5)
Substitution method
Direct equivalent
Consumption basis
Type-approval
Real-world
Chosen-type
Energy unit
MJ
kWh
1 kWh = 3.6 MJ. Efficiencies are unchanged; only the energy figures are converted.
Vehicle
Back to the reference weight
Efficiency of each link
Back to sourced values
Energy price
Tariff applied
Overall efficiency
—
well to wheel
Primary energy
—
per 100 km
Running cost
—
per 100 km
Sankey diagram of the energy flow, from the well to the wheel
Download SVG
Download PNG
Show the values as a table
Link Efficiency Energy left Loss
Compare every configuration (sourced values, reference weight, default settings, always well to wheel)
Configuration Efficiency Primary energy Cost / 100 km
Main source: JEC Well-to-Wheels report v5, JRC / EUCAR / Concawe, 2020 (EUR 30284 EN). Same C-segment reference vehicle throughout. The JEC vintage selector switches between the two columns the report itself publishes side by side: 2015 / NEDC and 2025+ / WLTP . Every default is read off the "Technology Walk" tables — 6-8 (petrol), 6-9 (diesel), 6-12 (hybrid), 6-17 (battery), 6-19 (fuel cell) — and each chain is then closed on the published consumption of Tables 5-6 ff. or 6-7/6-11/6-16/6-18, to within 0.2%.The vintage switch moves three things at once — cycle, technology and vehicle mass — and they partly cancel. The battery car's on-board loss budget is 370.0 kJ/km in 2015 and 372.1 in 2025+, all but identical, although every line inside it moves by 5 to 25%. Useful work rises from 22.23 to 26.44 MJ/100 km (rolling 90.0→95.6, air drag 132.3→168.8 kJ/km): the WLTC is faster, so drag grows as the square of speed and eats the aerodynamic improvement. That is why efficiencies jump while consumption barely falls — do not read the 2025+ column as a pure technology gain. Useful energy is taken from the battery-electric column and applied to every powertrain, iso-service; the JEC's own spread across powertrains is 21.9–23.0 MJ/100 km in 2015 and 26.1–27.0 in 2025+. Energy dissipated in the brakes is not counted as useful.Prices: surveyed on 4 August 2026 (EDF Tarif Bleu of 1 August 2026, prix-carburants.gouv.fr, h2.live). Primary-energy conventions: IPCC AR5, Annex II, §A.II.4. Upstream factors (extraction, refining, generation, grid) do not depend on the driving cycle and are shared by both vintages.Speed profiles. The Chosen-type mode borrows its four phases from the WLTC (Reick et al. 2021, Kia e-Niro on a chassis dynamometer) and applies them as ratios normalised to 1 on the reference cycle. On the 2025+ vintage that is native. On the 2015 vintage it is not — the shape across phases is measured, but the level stays NEDC, which is gentler than the WLTC, so absolute consumption there is understated.Licence. Text, figures and data © 2026 Robin Girard, MINES Paris — PSL, under CC BY 4.0 ; the code under the MIT licence. Reuse it in your own teaching, translated or cut up — just say where it came from. The JEC report itself keeps its own terms, and it, not this page, is what you cite for a JEC figure.Caveats: the upstream factors for electricity and hydrogen remain provisional (± 5%), as they could not be cross-checked in the source report. Grid-mix compositions are rounded 2024 generation shares and are indicative only. The Real-world gaps were measured against NEDC type approval and are an upper bound on the 2025+ vintage — the OBFCM-based figure has not been sourced. The 2025+ column is a JEC simulation of a projected vehicle, not a measurement.