Sweden’s AP7 has warned of a lack of transparency within the car industry, after several of the world’s largest manufacturers failed to disclose details of their lobbying efforts over emissions legislation.

Ford, PSA Peugeot Citroën (PSA) and Renault/Nissan are alleged to have failed to engage with an investor group worth £625bn (€842bn), which in October wrote to 10 car manufacturers requesting they disclose their contribution to lobbying work undertaken by the European Automobile Manufacturers’ Association (EAMA).

The consortium – which includes three of the AP buffer funds, AP7, the UK’s Environment Agency Pension Fund and Finland’s Ilmarinen – did receive responses from seven companies, praising Toyota, Honda, General Motors and BMW for providing a “good degree” of information.

But Charlotta Dawidowski Sydstrand, environmental, social and governance manager at AP7, said the lack of responses from several large companies revealed a problem within the industry.

“From a long-term investor’s perspective, this is bad news,” she said. “Lack of transparency impairs the ability of the market to price risks properly.

“AP7 wants to be reassured carmakers’ political lobbying activities are contributing to a safe climate, in turn protecting the long-term value of our portfolios.”

Action by the coalition of investors came in the wake of Volkswagen’s admission last year that it used software to beat emissions tests.

According to a statement released by ShareAction, the German car manufacturer responded to the coalition’s requests but “made no mention of the scandal and its implications in its response”.

WHEB Group – which, alongside AXA Investment Managers, also supported the October letter – said the Volkswagen “debacle” had firmly established the importance of vehicle emissions, and that leading companies were capable of demonstrating “coherent” strategies.

Seb Beloe, head of research at WHeB, added: “The lack of response from other companies including Nissan/Renault, Peugeot, Citroen and Ford raises real questions about the approach these companies are taking to this issue and potentially undermining their ability to maintain share in markets characterised by rapidly strengthening emission standards.”

ShareAction, the UK charity that helped coordinate the letter, also noted that fellow German manufacturer Daimler only issued a one-line statement arguing there was “no reason to be concerned” by its involvement with the legislative process.

The charity’s chief executive Catherine Howarth praised the asset owners backing the initial letter.

“The investors that came together to question global automakers on their lobbying activities have done the wider market a service in helping identify those car makers that remain unwilling to come clean about this murky and increasingly risky aspect of their business,” she said.