Diesel cars emit less carbon dioxide per kilometre than equivalent petrol cars.

Is it true that Diesel cars emit less carbon dioxide per kilometre than equivalent petrol cars?

Partly. Several sources state that diesel cars emit less carbon dioxide than equivalent petrol cars, including a chassis-dynamometer study finding a petrol direct-injection vehicle emitted 25% more CO2 than diesel vehicles, and a BMJ news item and an EU fleet study repeating the fuel-efficiency rationale. However, an EPA page reports higher CO2 per gallon for diesel than gasoline, and a climate study argues diesel cars may warm the climate more per distance once black carbon is counted, so the evidence covers the claim only in part and points both ways.

Verdict: CONTESTED PARTIAL · 2 sources for, 2 against · Last checked 2 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Switch to diesel engines is significantly to blame for poor air quality in UK cities, experts say. (2014). doi.org. https://doi.org/10.1136/bmj.g3033

Greenhouse Gas Emissions from a Typical Passenger Vehicle | US EPALockPrimary navigationOpen Sidenav MenuClose Sidenav Menuexpand or collapse the child menuexpand or collapse the child menuexpand or collapse the child menuexpand or collapse the child menuexpand or collapse the child menu. (n.d.). epa.gov. https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle

European CO2 change from the increased percentage of diesel passenger cars in European Union. (2007). doi.org. https://doi.org/10.4271/2007-01-1947

Control of fossil‐fuel particulate black carbon and organic matter, possibly the most effective method of slowing global warming. (n.d.). cir.nii.ac.jp. https://doi.org/10.1029/2001jd001376