Methodology

This page explains how the CarPairly tools turn prices, specifications and energy costs into a five-year cost of ownership, a charging cost and a real-world range estimate, and what the data cannot tell you. Where each number comes from is on the data sources page.

Total cost of ownership

Total cost of ownership (TCO) is what a car costs you over the years you own it, not just its price. The calculator compares two or three cars, electric and gas mixed, in one market. Every amount is in that market's currency, over a fixed 60 months.

The steps the calculator follows

1. Net price is the purchase price minus any incentive you enter.
2. The loan is the net price minus your down payment, never below zero. A blank APR means a cash purchase.
3. With an APR, the monthly payment is the standard loan payment for your term. With 0%, it is the loan divided by the months. Interest counts only what is paid within the 60 months.
4. Energy per year depends on the powertrain, as set out below.
5. Insurance and maintenance are yearly amounts, counted for five years.
6. Resale value is the purchase price multiplied by one minus the five-year depreciation rate.

The total over five years is the net price, plus interest, plus five years of energy, insurance and maintenance, minus resale value. Dividing by five gives a yearly figure, and dividing by five years of distance gives a cost per kilometer or mile.

Energy by powertrain

• Electric car (BEV): yearly distance times the car's energy use per kilometer times the electricity price per kWh.
• Gas car, hybrid (HEV) and diesel: yearly distance times the car's fuel use per 100 km, divided by 100, times the fuel price.
• Plug-in hybrid (PHEV): a share of the distance on electricity and the rest on fuel. You can change the electric share. If the car's electric consumption is missing, the tool asks you for it.

What the calculation leaves out

It does not discount or inflate future costs. It has no recurring road tax term. It does not convert between currencies: the market's own currency is the only currency in the result.

Assumptions and estimates

Where you leave a field blank, the tool uses a default. The purchase price defaults to the current base-trim price in the market, with its tax treatment, check date and source link. Energy prices come from the stored price for that market, with the period and source shown. Defaults that are assumptions, such as yearly distance, maintenance and depreciation, each have a source and a check date, and the calculator labels them "Estimate".

The cost assumptions in use are listed with their source link and check date in the tool's "Assumptions used" table. Where no sourced value exists, the tool asks for your own value instead of guessing. Every result shows the numbers it used, and the result link carries your inputs.

Charging cost

The charging cost tool works from the car's usable battery capacity and the electricity price per kWh of the market. The energy for a charge is the usable capacity times the share of the battery you charge: from 10% to 80% for a fast-charge stop and from 0% to 100% for a full charge. The cost is that energy times the price per kWh, rounded to cents. The cost of 100 km (or 100 miles) is the car's energy use times the price per kWh.

The result is the cost of the energy that reaches the battery. Losses between the wall and the battery are not included, because no sourced figure for them is available.

Electric energy use: stored and derived

The charging cost tool, the five-year cost calculator and the energy cost rows on car and compare pages need the electric energy a car uses per kilometer. Where we hold an official or sourced figure for the test cycle in use (WLTP or EPA, whichever the market prefers), the tools use it, and a stored figure always wins.

Where none is stored, a battery-electric car with a known usable battery capacity and a rated range gets a derived figure: usable battery capacity divided by the rated range of the same test cycle. It is labelled "Derived: usable battery divided by rated range" (short form "Derived") wherever it is used. It is the energy at the battery, so it leaves out charging losses between the wall and the battery, which official label figures such as the EPA's include. A derived figure therefore tends to be 10 to 20 percent lower than an official one for the same car. A plug-in hybrid never gets a derived figure, because its rated range mixes electricity and fuel.

Derived figures feed cost calculations only. Specification tables, rankings, peer comparisons and highlights show and rank stored figures only, so a derived number is never ranked against an official one. On a comparison page, two derived costs on the same test cycle and the same tax basis may be compared. A derived cost is never compared with one based on an official label figure, and costs based on different test cycles are never compared.

Electricity prices

The cost tools use the stored electricity price of the market, with its period and its source shown. Electricity prices for the United States, Canada and Australia are entered by hand from the official publications named on the data sources page, and each carries a source link and a check date. Prices for other markets come from the sources listed there too.

Australia has no single national price in our data. The Australian price is the Default Market Offer 2026-27 of the Australian Energy Regulator for the Ausgrid network area in New South Wales. The tools say so beside the price, for example "New South Wales (Ausgrid)" followed by the source, so a New South Wales price is never passed off as a national one. Prices elsewhere in Australia can differ. The rule is general: when a market has no national electricity price and exactly one regional price, the tools use that regional price and name the region. When a market has several regional prices and no national one, the tools show no price instead of averaging them.

Real-world range

The real-world range tool starts from the car's rated range and its test cycle. The estimate is the rated range times a temperature factor times a speed factor. Each factor belongs to a band (for example a temperature band), and the two factors are applied independently, one after the other. Nothing is interpolated between bands. Every factor has a source and a check date. The tool is not available yet. It opens once sourced factors exist for both temperature and speed, so no estimate is shown on guesses.

Prices, tax and currency

Prices on CarPairly are list prices as published by the source on the date shown next to them. Each price carries a tax flag, so you can see whether it includes VAT or sales tax.

For list prices that come from OpenEV Data, the source does not state a tax status. We therefore apply the market convention: United States and Canada list prices exclude sales tax, and list prices in the other markets include VAT or GST. Each such price carries the note "tax status assumed by market convention, not stated by the source". Australian prices also note that on-road costs are not stated.

Prices are never overwritten: a new price closes the old one and starts a new one.

When a price is shown in a currency other than its own, we use the latest European Central Bank reference rate on or before the display date, through the euro for cross rates. The amount is marked with "≈" and the rate date. Converted amounts are never stored. Next to the official price, a small second line can show the same amount in your own currency. It is approximate: it uses the latest European Central Bank reference rate that is no more than 7 days old, starts with "about", names the rate date and rounds larger amounts to three significant digits. Your browser draws it, so it needs JavaScript, and it is never part of the stored price. The official price is always the price in the market's own currency.

Specifications and units

We store every measurement in metric units and convert it for display: miles and mpg (US) in the US, miles and mpg (UK) in the UK, kilometers and L/100 km elsewhere. Range figures name their test cycle, WLTP or EPA. These are different lab tests, and a lab figure is not what you will get on a cold motorway drive.

When a value is missing it is hidden, never shown as zero. Cargo volume is the most common gap in the open data we use.

OpenEV Data has no size class (segment). Where we show one, we derive it from body length using fixed bands, which are our rule rather than an industry standard.

Data quality and limits

• The electric car catalog is built from OpenEV Data release v1.24.0, generated on 30 December 2025. This release covers battery electric cars only, model years 2023 to 2025, and contains no 2026 models. Gas and diesel cars are entered by hand from the manufacturers' pages, each with its source link and check date.
• We have not independently verified every figure in that release. Each record names its own sources.
• When an automated feed sends a number that differs by more than 30% from the stored value, we hold it for a person to review instead of publishing it.
• If a source cannot be fetched, we keep the previous value instead of removing it.

OpenEV Data attribution

Vehicle specifications and some list prices: OpenEV Data (open-ev-data), CDLA-Permissive-2.0. https://github.com/open-ev-data/open-ev-data-dataset

Release v1.24.0, accessed 2 October 2026. License: CDLA-Permissive-2.0 (Community Data License Agreement - Permissive, Version 2.0), https://cdla.dev/permissive-2-0/.