Volkswagen's incredibly popular Polo supermini emits as much nitrogen dioxide pollution as a fully laden lorry, a study has revealed.
Researchers at Leeds University's Institute for Transport Studies found that the diesel-powered Polo emitted 13 times more NO2 emissions than EU law allows, and is one of the most polluting cars in the UK.
James Tate, the study's lead researcher, told the Daily Mail: "The worst-performing car [in the tests] was a VW Polo with a 1.4-litre turbodiesel engine with NO2 emissions 13 times higher than EU regulations allow.
"Its emissions of 1.2 grams of NO2 per kilometre were the same as a fully laden diesel truck with a 13-litre engine that we also tested."
The study, which was commissioned by Transport for London, was performed by vehicle-testing organisation Millbrook. In all, 13 diesel-powered cars and four lorries were involved.
It recorded acceleration, cruising and deceleration patterns from around London at different times of the day, and then replicated them on rolling roads so emissions could be accurately measured.
Tate said: "The key finding was that small diesel cars emitted far more pollution than larger cars and even lorries."
The cause of the smaller cars' high pollution levels is the lack of on-board space for advanced emissions controls. Tate also added that these technologies can bump up the prices of these small, affordable cars.
"For cheaper cars the technology is too expensive and there may not be enough space to fit all the extra components," he commented.