With the global emphasis on reducing average CO2 emissions, it is a mystery why gas power for cars is rare in Europe — especially given that gas-powered buses are very common.

It’s ironic that the Volkswagen Group, which triggered the great diesel scandal, made the decision years ago to incorporate gas tanks into its MQB and MLB platforms.

At the Geneva show in March, Audi displayed its gas-powered MLB platform under the new A5. Equipped with a 25-litre back-up petrol tank, the car is good for 100g/km of CO2. Without the petrol tank, it’d probably be an 80g/km car, close to an electric car charged off the UK grid. In fact, because gas accounts for around 40- 50% of power generation in the UK, an electric car is in effect partly gas-powered in any case.

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More to the point, using natural gas massively reduces what should be the real issue: tailpipe pollutants. NOx emissions should drop by 80% and particulates by 99%.

Audi says a gas-powered A5 will cost the same as the diesel but needs far less in the way of exhaust after-treatment. Compared with an electric car, it is lighter, is much less expensive and isn’t full of complex battery technology. For the next 10-15 years, gas makes more sense and is arguably greener than battery power.