The study, entitled "How They Did It: An Analysis of Emission Defeat Devices in Modern Automobiles", was conducted by academics from Germany's Ruhr-Universität Bochum and the University of California, was part-supported by the European Research Council. The implications were published by Bloomberg.
Two modes were found to be used to cheat emissions tests, ‘real driving’ and ‘homologation’, with the latter designed to recognise when the car was under test conditions, and the former to be used by the car’s intended customers.
Affected engines are fitted with Bosch’s EDC17 ECU, which the study says was programmed with the defeat software.
“Notably, we find strong evidence that both defeat devices were created by Bosch and then enabled by Volkswagen and Fiat for their respective vehicles,” the report says, although only the Fiat 500X SUV is implicated.
Similar allegations were made against Bosch last year, when a lawsuit filed by representatives of affected vehicles in the US accused the supply giant of being a “knowing and active participant” in the emissions manipulation. Bosch responded by saying that it is not responsible for how a manufacturer uses its components.
A Bosch spokesman said: "As a matter of policy, and due to the sensitive legal nature of these matters, Bosch will not comment further concerning matters under investigation and in litigation."
Autocar is awaiting responses from Volkswagen and Fiat.