Germany is the only major European country that has not approved aid to keep Opel and British sister brand Vauxhall afloat with money backstopped by taxpayers.
Germany has advised it will offer aid on the condition that proof the German based, GM Co. unit, did not fall into difficulty before summer 2008 as a direct result of the financial crisis.
Opel Deputy Chairman Klaus Franz, says PricewaterhouseCoopers, the economics ministry's own independent expert, certified Opel was profitable until September 2008.
"The German government needs to act immediately because 120,000 jobs in Germany dependent on the carmaker are at stake," Franz says.
Opel CEO, Nick Reilly, who expects a final answer from Berlin by the end of this month, says generous contributions from other main Opel countries likely Spain and the UK meant Germany may be on the hook for less than 1.3 billion euros.
Relations between Berlin and Detroit has been frosty since November when GM scrapped the sale, heavily favoured by Chancellor Angela Merkel, of a majority stake in Opel to Magna International Inc.
GM initially saw funding responsibility to its European subsidiary as completed once it paid back the remaining 600 million euros of an emergency loan from the German government, which Detroit needed to do by the end of November to regain 65 percent of the shares held by a trustee.
The U.S. carmaker realises Berlin will not lift a finger following November's rift unless GM provides more of a commitment.
In March, GM said it would commit 1.9 billion euros in loans and even fresh capital to Opel.