Germany's Social Democrats (SPD) on Saturday refused to absolve the country's carmakers of their responsibility for reworking exhaust systems in old diesel vehicles.
"We unconditionally need a technical retrofitting of these vehicles, which is more economic than making a new purchase," deputy chairman of the SPD's parliamentary faction Soeren Bartol told dpa.
On Friday, German automaker Volkswagen announced its plan to offer a "trade-in bonus" to the owners of older diesel vehicles in Germany.
Similar incentives have already been announced by BMW, Daimler, Ford and Toyota.
Many owners of older cars cannot afford new vehicles, so the German proposal of a rebate on a new vehicle purchase represents "only one possible solution," Bartol said.
The comments signal the SPD's attempt to distance itself from German Chancellor Angela Merkel's Christian Democrats, who are historically champions of business interests and have been seen as having a cozy relationship with the country's auto industry.
German carmakers have come under increasing pressure in the wake of Volkswagen's admittance in September 2015 that it had installed instruments that cheated diesel emissions tests in more than 11 million vehicles worldwide.
A Stuttgart court ruled last week that diesel cars failing to meet emissions standards could be banned from the southern German city on certain days, possibly paving the way for other cities to follow suit.
That ruling turned up the pressure on carmakers to find a solution for reducing emissions.
