The majority of signatories who wrote to the European Union (EU) disputing the benefits of electric cars on greenhouse gas emissions are petrol or diesel experts, according to a climate change news outlet.
DeSmog also reports a third of those signing had past or present affiliations with motoring companies and none have "any apparent expertise in electric vehicles (EVs)".
The International Association of Sustainable Drivetrain and Vehicle Technology Research (IASTEC) wrote the letter in June, claiming the EU had miscalculated the effectiveness of EVs in cutting greenhouse gas emissions.
Several of the signatories couldn't be verified, while eight of them were repeated, DeSmog also reported.
Julia Poliskanova of environmental organisation Transport & Environment told the website she believes the IASTEC is clearly a group driven by vested engine interests and not independent scientists.
Researcher Auke Hoekstra, from Eindhoven University of Technology, took to Twitter to claim the "combustion engine lobby is gaslighting again".
He concluded IASTEC's study didn't show an EU calculation error underestimating CO2 emissions of EVs, but "instead it proves that the authors are pretty clueless".
Energy systems modeller Tom Brown, a quantum physics scientist who now makes energy models, concluded the paper was "over-complicated and amateurish for its simple message and would not have been published in an energy economics journal".
IASTEC describes itself as an "international association of professors and researchers worldwide working on vehicle and drivetrain research at famous universities".
Professor Thomas Koch, listed on the IASTEC website as contact for the group and is one of the lead authors of the paper, defended the group, telling DeSmog it was "an academic initiative without any interaction of industry".
Koch, who worked for German car manufacturer Daimler for 10 years, said the paper does "emphasise the necessity of battery EVs for plenty of applications. it also emphasises the necessity of alternative technical solutions".
Poliskanova said it was time to stop questioning EVs and accelerate their uptake for the sake of the planet, with "electric cars today already significantly better for the environment than the oil engines they replace".
Meanwhile Tesla CEO Elon Musk has revealed the Tesla Roadster EV, originally scheduled to begin production in 2020, "should ship in 2023", providing there are no major drams.
"2021 has been the year of super crazy supply chain shortages, so it wouldn't matter if we had 17 new products, as none would ship," he tweeted.
Last month it was revealed that the company's CyberTruck was delayed until 2022 after months of speculation.