Does an EV really have higher manufacturing emissions?

Yes. Building an EV, mainly its battery, emits more CO2 up front than building a comparable petrol car, typically several tonnes more. The EV repays this 'carbon debt' through cleaner running, and this tool shows the distance at which it breaks even.

How is battery-manufacturing carbon estimated?

It is approximated as the battery capacity in kWh times a manufacturing factor of around 70 kgCO2e per kWh of cell capacity. A 60 kWh battery therefore carries roughly 4.2 tonnes of extra embedded carbon, amortised across the vehicle's life in the comparison.

What grid intensity should I use for the EV?

Use the grid where you charge. On a clean grid an EV's running emissions are tiny and it breaks even quickly; on a coal-heavy grid the running advantage shrinks and break-even takes far longer. The grid factor is the single biggest variable in the EV result.

Is the EV always cheaper to run?

Usually, because electricity per mile costs less than petrol or diesel in most markets, especially on an off-peak tariff. But high electricity prices or very cheap fuel can narrow or reverse the gap, which is why the tool computes cost from your own figures.

What does the break-even distance mean?

It is the lifetime distance at which the EV's lower running emissions have fully repaid its higher manufacturing emissions, so total CO2e becomes equal. Drive further than that and the EV is cleaner overall; drive less and the petrol car may have emitted less in total.

EV vs Petrol Lifetime CO2 & Cost Comparator

Whether an electric car is genuinely cleaner than a petrol one depends on how far you drive, how clean your grid is, and how big the battery is. This comparator models 10-year lifetime CO2e and running cost for both, including the EV’s higher manufacturing carbon, and shows the distance at which the EV pulls ahead.

How it works

ICE running CO2  = distance_km × (litres/100km ÷ 100) × fuel CO2 per litre
EV running CO2   = distance_km × (kWh/100km ÷ 100) × grid gCO2/kWh ÷ 1000
EV battery CO2   = battery_kWh × 70 kg/kWh  (added once, up front)
break-even km    = EV battery CO2 ÷ (ICE per-km − EV per-km)

Petrol emits about 2.31 kgCO2 per litre and diesel about 2.68. The EV’s running carbon scales directly with your grid intensity, so a clean grid makes the EV break even within a year or two, while a dirty grid pushes it out.

Cost of ownership

Running cost is fuel or electricity per distance over the chosen lifetime. EVs usually win on running cost because energy per mile is cheaper, but the result depends on your local fuel price and electricity tariff, both of which you enter.

Notes

The 70 kgCO2e/kWh battery factor and 10-year default are typical modelling assumptions; adjust mileage, grid, and prices to your own situation. The tool deliberately separates the EV’s up-front carbon debt from its running savings so you can see exactly when, in distance, the EV becomes the lower-carbon choice.