The KBA said that although the tests were triggered by Volkswagen's admission it had rigged tests, there had been “verified indications from third parties regarding unusual pollutants emissions”.
“Since the end of September KBA has been investigating whether further manipulation of emissions, of nitrogen oxides in particular, is taking place in the market,” KBA said in a statement.
Germany's Transport Minister Alexander Dobrindt said in an interview over the weekend that diesel vehicles, including those from foreign manufacturers, would be subjected to strict checks.
As well as Volvo, now owned by the Zhejiang Geely Group of China, other manufacturers being tested include BMW, Nissan, Mercedes and Toyota.
VW admitted in September to cheating tests for emissions of nitrogen oxides.
The scandal widened last week with VW's revelation that it had also understated carbon dioxide emissions.