Per Kågeson wrote about the technologies that allow cars to pass emissions tests but have higher pollution levels when they are used by ordinary drivers in a major EU report in 1998.
"Tests carried out by the Swedish exhaust emission laboratory Rototest AB reveal that some manufacturers do not take responsibility for the exhaust performance of all or some of their models in situations when the car is driven under conditions not covered by the official European test cycle," said the paper.
"This kind of 'cycle beating' results in high emissions of carbon monoxide, hydrocarbons and ammonia," the document continued.
"I warned, learn about the engines' computer control in order to know when the vehicle is running under the test cycle in order to optimize exahust gas purification," the Swede, who is now 68, told Swedish newspaper Dagens Nyheter (DN) on Tuesday.
He said that not enough had been done since the 1990s to make it more difficult for manufacturers to beat the tests and singled out the German carmaker VW's approach to emissions.
"What kind of ethical values did Volkswagen Group (VW) instill in its employees to allow this kind of thing to happen?" he questioned.
In addition, the expert said that if new tougher European tests set to be introduced in 2016 had come into place previously "the extent of the cheating would have been very much lower."
Kågeson's critique came as reports suggested that the VW emissions testing scandal could speed up stalled EU talks designed to lead to more accurate measures.
EU industry commissioner Elzbieta Bienkowska was scheduled to meet top Volkswagen bosses in Brussels on Tuesday, according to Belgium-based publication EU Observer, before debating the issue with EU competition ministers in Luxembourg later in the week.
Both the European Commission and national governments are continuing to face criticism for either failing to realize that the emissions scandal was on the cards, or failing to recognize advice from campaigners such as Kågeson.
In addition to the Swede's research, report by the Commission's Joint Research Centre in 2013 warned that car emissions tests could be misleading, but did not take immediate action on this information.
The scandal broke when US officials publicly accused Volkswagen of cheating and launched a probe which has also seen a growing list of other countries launch investigations.
The German carmaker has since admitted that 11 million vehicles worldwide could be affected by software that covertly turns on pollution controls when the car is being tested, and off when it is being driven.
Volkswagen's CEO Martin Winterkorn resigned amid the emerging scandal, and he is under investigation in Germany.