Nineteen investors including AXA Investment Managers, the fund arm of insurer AXA (>> AXA), and the Swedish national pension fund, wrote separate letters to 11 major automakers, retail investor watchdog ShareAction said in a statement.

Volkswagen , BMW (>> Bayerische Motoren Werke AG), Honda (>> Honda Motor Co Ltd), Daimler (>> Daimler AG), General Motors (>> General Motors Company), Ford (>> Ford Motor Company), Fiat , Peugeot (>> PEUGEOT) and Toyota (>> Toyota Motor Corp) all received letters requesting information on lobbying around emissions rules being debated in the United States and the European Union.

Another letter was sent to Carlos Ghosn, chief executive of Nissan (>> Nissan Motor Co Ltd) and Renault (>> Renault), as both have been recognised as some of the best performing companies for CO2 emissions, the statement said.

The initiative comes after VW admitted rigging diesel emissions tests, knocking billions of euros off VW's stock market value and throwing the spotlight on practices across the industry.

"When it comes to the engagement underway between a company and the key regulations affecting it, there are often sparse details available to investors," Dylan Tanner, executive director at non-profit group InfluenceMap, which analyses and ranks companies on climate lobbying and influence, and which helped coordinate the sending of the letters.

"The Volkswagen case highlights the need for a much greater disclosure regime, both of the company's specific position on key legislation and its involvement in the policy process."

(Reporting by Simon Jessop; Editing by David Holmes)