Tim Holden, chief executive of Holden Group, breaks his holiday resolution to look at a diesel dilemma.

One of the things I like about a holiday is not keeping up to date with current affairs. Switching the smartphone off, not going near a TV or a newspaper and forgetting the rest of the world exists.

This year I made a holiday resolution to carry on in blissful ignorance as long as I could. I managed 14 hours before, in the supermarket buying all the things we had managed to eat before we left, I saw in the Daily Telegraph:

Diesel drivers to be penalised in drive to cut air pollution

Despite my resolution, I knew I would have to find out what that was all about.

In short, diesels, now the majority of the UK population own one, are suddenly evil and must be eradicated. According to some anyway, notably Boris Johnson, because they emit nitrous oxide which isn't good for you when you inhale it.

The government introduced the current vehicle excise duty in 2001, bringing the UK in line with Europe, with the main criteria CO2 emissions. CO2 is bad for the ozone layer and, as a consequence, all of humanity. The more your car emits, the more you pay. Environmental box: ticked.

Car-makers delivered huge increases in fuel economy and big cuts in CO2. Diesel engines perform better than petrol so, inadvertently, the government's focus on CO2 incentivised the production and sales of diesel cars. Looking at every car (excluding electric) we sell at Holdens, average fuel economy and road tax is 73.1mpg and just £14.57. Consequently, most people are buying diesel.

Seeing as 59% of the diesel pump price is tax, such gains on both fronts must have led to a large drop in tax revenue to the Treasury? Ahem.

Another benefit of diesel engines is they reach their most efficient operating temperature in about half the time of a petrol unit so emit less carbon monoxide, hydrocarbons and lead – none of which should be inhaled – than petrol. It's an advantage in urban areas where most vehicles are but, unfortunately for diesel, you get more nitrous oxide and particulates.

So which is better? I have no idea. I think I preferred being in blissful ignorance on the whole subject. My conclusion is a new modern car – diesel or petrol – is considerably kinder to the environment than your current five-year-old motor.

I would say that, wouldn't I? I have a holiday to pay for!

Tim Holden is chief executive of Holden Group.