Volkswagen’s Diesel Dilemma

In the wake of the revelations about VW’s use of defeat devices to pass emissions regulations, our Tom Harrison asks: Have diesels had their day?

Volkswagen have recently been caught cheating. They admitted fitting a device to their cars that allowed them to cheat emissions tests.


The so called defeat device was able to detect when the car was under test conditions, and electronically alter its performance to limit the nitrogen oxide (NOx) emissions to around 2.5% of the true value. Technically, it was a brilliant solution: it worked, was cheap, and wasn’t strictly illegal. It was also a deeply immoral and, frankly, moronic decision, given the warnings VW had received from from the EU and the manufacturer (Bosch).

Volkswagen did this in order to comply with very strict American regulations on nitrogen dioxide (NO2) emissions. Nitrogen oxide is a greenhouse gas: 100 times more potent than CO2, and a pollutant that causes acid rain, damage to the ozone layer and smog. NO2 is a particular problem for diesel engines, and the defeat device meant they didn’t have to fit bulky filters that lessen performance and can add as much weight as an extra passenger.

These strict regulations were originally a protectionist measure. Diesel cars are predominantly made by European manufacturers and American lawmakers wanted to make it harder for VW to compete in the US. It wasn’t until later that the environmental effect was discovered.

volkswagen-652926_1920For many years diesel was sold as a more eco-friendly alternative; it gave a better fuel economy and marginally better CO2 emissions. It is only recently these secondary pollutants have become a limiting factor in the regulations. Technology is moving on – we have reached the limits of conventional fuels, petrol engines offer superior efficiency and emissions, and electric cars (along with hybrids) can give superior performance with significantly reduced emissions.

This scandal has exposed not just VW, but the short comings of the diesel engine as a method of propulsion. This could be the turning point in the industry. Diesels may be about to drive into the sunset of history.

Tom Harrison is a third year Automotive Engineering student and the Warwick Globalist’s Science & Technology Editor. He is currently doing a project on electric vehicles and is Treasurer of Warwick International Relations Society.


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