Lawmakers are formulating “meaningless” green vehicle regulations, according to Andy Palmer, CEO of British luxury car manufacturer Aston Martin.

He said authorities were committing a fundamental misstep by stipulating what technologies should be adopted, referring to Britain’s July announcement that it would ban the sale of new petrol and diesel cars by 2040. The regulation was aimed at reducing air pollution.

“Policy makers should not try to be engineers,” Palmer quipped, adding that the announcement was “just spin” without any practical meaning.

“In my view as an engineer, it’s better to prescribe the emission, and then let the engineers figure out what the right technology is,” he said.

According to Palmer, the danger in the car ban lies in authorities’ lack of knowledge about which engineering solutions best suit their objectives. By refining existing technology, gasoline cars can almost double their fuel economy — a feat that is already a reality with Formula 1 speeders, which put 50 percent of the energy produced into moving the car, the CEO said.

That improvement, if applied to internal-combustion-engine passenger vehicles, would mean an almost 50 percent cut in carbon emissions for a given mileage.

In contrast, “if you take today’s engine and you simply slap a hybrid on, you end up more or less in the same place,” he said.

Palmer added that policymakers were also muddled about the problem they are trying to mitigate in the first place.

“Are we trying to solve clean air? In this case, ban diesels. Or are we trying to solve CO2? In this case, you need to use less fossil fuel,” he said. “The two are different. And a lot of the dialogue right now is mixing those messages.”

Cars that run on fuel produce carbon dioxide along with other greenhouse gases. Diesel vehicles, however, emit more pollutants, such as soot and nitrogen oxides, as compared with their gasoline counterparts. Those emissions can cause lung and other bodily irritations and may also induce cancer, according to the U.S.-based Union of Concerned Scientists, an independent science and advocacy organization.

Palmer added that the impending ban on sales of petrol and diesel cars still wouldn’t make it possible for the auto market to become fully electric by 2040, as he didn’t think batteries would be sufficient to power heavy vehicles.

Instead, it’s more likely that “about half the cars will be gasoline and gasoline hybrid, and about half the cars will be alternative fuel,” he said.

To be sure, electric vehicle maker Tesla announced earlier this month that it planned to launch in October a semi truck, which Reuters reported would have a range of around 200-300 miles, compared with an around 1,000-mile range for conventional models.

Aston Martin will continue to heavily feature its iconic gasoline V12 engine in its lineup, according to Palmer.

However, he said the company also plans to produce purely electric and gasoline hybrid cars to move toward the zero-emission target, which U.K. Prime Minister Theresa May’s Conservatives had pledged to achieve by 2050.

The company has seen a turnaround since Palmer took the reins in 2014, and earlier this year registered its first half-yearly profit in a decade. Its earnings were boosted in part by the launch of its new DB11 model, and the firm plans to release a new model every year.

Along with Britain, France and China have in recent months also led the push toward increasing the adoption of electrics, and moving away from traditional fuel-run cars.