The episode of Dispatches entitled ‘The Great Car Con’ was aired on Monday 26 January and called the reliability of performance and pollution figures provided by car manufacturers into question and found a worrying link between diesel-engined vehicles and the levels of harmful nitrogen dioxide that drivers of these are exposed to.

In tests Dispatches found that the level of the toxic gas nitrogen dioxide which drivers are exposed to was 37 microgrammes per cubic metre – dangerously close to the 40mg safety limit. This compares with 30mg for bus passengers, 23mg for pedestrians and 14mg for cyclists.

Halfords fuel additive product manager Jemma Billings said: ‘The news that they may be using more fuel and creating more pollution than both car makers and the government have implied, whilst also potentially harming their own health, has clearly provoked a reaction among the owners of diesel cars.

‘Fuel additives that clean diesel filters, catalytic converters and the fuel injection system on cars are an effective way of ensuring a vehicle is operating as efficiently as possible and, because they can easily be poured into your tank when filling up, drivers have taken what steps they can to address the problem themselves.’

The increase in demand that Halfords has witnessed is specific to diesel fuel additives – though petrol variants are also available – with seven different product lines seeing double-digit growth ranging from 16% to 42% over the past week.