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What is the average CO2 emissions per diesel car?

There isn’t a single universal number for the average CO2 emissions of a diesel car. Emissions depend on the model, its size and weight, the driving cycle used for testing, and regional regulatory standards. In Europe, new diesel passenger cars typically fall into roughly the 110–130 g CO2 per kilometer range under WLTP testing, with smaller diesels nearer the lower end and larger diesel SUVs higher. Outside Europe, published averages by fuel type are less common, reflecting market differences and data availability.

Regional variations in diesel CO2 emissions

The following overview summarizes how emissions from diesel passenger cars tend to differ by major market, noting that exact figures vary by model and year and are affected by the testing cycle used.

Europe (including the UK): Typical new diesel passenger cars emit about 110–130 g CO2/km on WLTP tests. Smaller, efficient diesels can be closer to the low end (around 100–110 g CO2/km), while larger diesel SUVs often exceed 130 g CO2/km.

United States and Canada: Diesel passenger cars are a small share of the market, and national averages by fuel type aren’t published as a single metric. Where available, CO2 figures for individual diesel models vary widely, but the market generally leans toward lower diesel activity compared with Europe.

Asia-Pacific and other regions: Data on diesel passenger-car CO2 emissions are more fragmented. In markets with limited diesel passenger-car sales, published per-model CO2 figures or fleet aggregates tend to be sparse and model-specific rather than a single regional average.

In short, Europe provides the most comprehensive published averages for diesel CO2 emissions by fuel-type, while other regions publish data mainly on individual models or through broader fleet reporting. This reflects both market size and regulatory differences.

What drives CO2 emissions in diesel cars

Several factors determine how much CO2 a diesel car emits per kilometer. Understanding these levers helps explain why there isn’t a single “average” figure and how different cars land at different points on the spectrum.

Engine size and efficiency: Smaller, more efficient diesel engines can keep CO2 relatively low, while larger, more powerful diesels push numbers higher.

Vehicle weight and aerodynamics: Heavier vehicles and less aerodynamic shapes require more energy to maintain speed, increasing CO2 emissions.

Drivetrain and transmission: More gears, all-wheel drive, and heavier transmissions can raise CO2, though efficient gear engineering can mitigate some of that increase on highways.

Testing cycle and real-world driving: WLTP provides more realistic numbers than older cycles, but real-world driving conditions (urban stop-and-go vs. long highway trips) can still produce higher CO2 than official test figures.

Emissions-control hardware and calibration: Diesel particulate filters and selective catalytic reduction address NOx and particulates; while they influence efficiency and weight, their direct impact on CO2 is typically smaller than that of engine and vehicle size.

The balance of these factors explains why a diesel car’s CO2 figure can vary widely even within the same class, and why buyers should look at model-specific WLTP numbers rather than broad generalizations.

Implications for buyers and policymakers

For buyers, the most reliable way to compare CO2 emissions is to review the WLTP-certified figures for the exact model and trim you’re considering, and to consider real-world performance where available. For policymakers, CO2 targets for new cars aim to push fleets toward lower emissions while balancing other concerns such as urban air quality and NOx/particulate controls linked to diesel technology.

Summary

There is no single, universal average CO2 emission figure for diesel cars. In Europe, new diesel passenger cars typically emit around 110–130 g CO2/km under WLTP, with some models far below or above that band depending on size and design. In other regions, data are more model-specific or limited due to market structure. The key determinants of CO2 emissions include engine size and efficiency, vehicle weight and aerodynamics, drivetrain choices, and the testing cycle used. Buyers should rely on model-specific WLTP numbers and consider how real-world driving may affect actual emissions.

What is the average CO2 emissions for a diesel car?

127.0 g CO2/km
On average, the CO2 emissions of diesel cars (127.0 g CO2/km) are now very close to those of petrol cars (127.6 g CO2/km). The difference of 0.6 g CO2/km was the lowest observed since the beginning of the monitoring. About 38 % of new car registrations were SUVs.

How much CO2 per gallon of diesel?

Burning one gallon of diesel fuel produces approximately 22.2 to 22.45 pounds (or 10.1 to 10.21 kg) of carbon dioxide (CO2cap C cap O sub 2𝐶𝑂2). This figure is based on the fuel's carbon content and its combustion in an engine.

Fuel	CO2cap C cap O sub 2𝐶𝑂2 per Gallon
Diesel	~22.2 to 22.45 pounds
Gasoline	~19.4 pounds

Diesel emissions: About 10,180 grams (or 22.45 lbs) of CO2cap C cap O sub 2𝐶𝑂2 are produced from burning one gallon of diesel fuel, notes the U.S. Environmental Protection Agency (EPA).
Comparison: Diesel fuel produces more CO2cap C cap O sub 2𝐶𝑂2 per gallon than gasoline, which generates about 19.4 pounds of CO2cap C cap O sub 2𝐶𝑂2 per gallon.
Calculation: The CO2cap C cap O sub 2𝐶𝑂2 emissions are calculated by multiplying the carbon content of the fuel by the ratio of the molecular weight of CO2cap C cap O sub 2𝐶𝑂2 to the molecular weight of carbon (44/1244 / 1244/12).

What is the #1 contributor to climate change?

The biggest contributor to climate change is the burning of fossil fuels (coal, oil, and gas) for energy, which releases greenhouse gases, primarily carbon dioxide. These activities account for approximately 68% of global greenhouse gas emissions, with transportation, industry, and electricity generation being major sectors.
Key contributing activities

Electricity, heat, and transportation: The burning of fossil fuels to generate power for homes and businesses, and to fuel vehicles, is the largest source of greenhouse gas emissions.
Industry: The energy used by industrial processes and the chemical reactions needed to create materials like cement and steel are significant contributors.
Agriculture and land use: Deforestation and other land-use changes release carbon dioxide, while agriculture is a major source of methane from livestock and rice cultivation.
Buildings: Heating, cooling, and powering buildings contribute to emissions, though energy efficiency improvements can help reduce this impact.

Other factors

While carbon dioxide is the most significant contributor, other greenhouse gases also play a role.
Methane is the second-largest contributor, with major sources including agriculture and natural gas leaks.
Chlorofluorocarbons (CFCs) and other fluorinated gases are also potent greenhouse gases, although their contribution has been reduced through regulations like the Montreal Protocol.

What is a normal CO2 emissions for a car?

The average passenger car in the U.S. emits about 400 grams of CO2cap C cap O sub 2𝐶𝑂2 per mile, which totals approximately 4.6 metric tons of CO2cap C cap O sub 2𝐶𝑂2 per year. New cars in Europe have lower average emissions, with 108.2 g CO2cap C cap O sub 2𝐶𝑂2/km in 2022, due to the increasing share of electric vehicle registrations.
Average U.S. emissions

Per mile: About 400 grams of CO2cap C cap O sub 2𝐶𝑂2 per mile.
Per year: Approximately 4.6 metric tons of CO2cap C cap O sub 2𝐶𝑂2 per year, based on an average of 11,500 miles driven and a fuel economy of about 22.2 miles per gallon.

Average European emissions (new cars)

2022: 108.2 grams of CO2cap C cap O sub 2𝐶𝑂2/km.
2023: 106.8 g CO2cap C cap O sub 2𝐶𝑂2/km.
Impact of EVs: The growing number of electric vehicles is a key factor in lowering the average emissions for new cars in Europe.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.