Managements at both companies primarily want more flexibility in working hours, but worker representatives are holding out for job guarantees and higher pay.
The main focus of the IG Metall metalworkers union is wage increases.
"Workers expect pay rises on October 1," said Hartmut Meine, IG Metall's regional manager responsible for Lower Saxony, where VW is based.
Meine threatened massive strikes, if the union's demands are not met.
Klaus Volkert, head of the VW works council, told Automobilwoche that "secure jobs are more important to me than a 1.5 percent pay rise."
He said that he would be fighting for other improvements in contracts. These would include better training and improved health care.
Josef-Fidelis Senn, head of personnel at VW, said: "We will need to redefine working hours in the long-term and treat the purely value-added issues differently from the non-value-added ones."
The situation at Opel has also become tense.
Klaus Franz, head of Opel's general works council, destroyed hopes of a quick result to the company's latest round of labor talks and said negotiations will likely continue through October 31.
"We want a contract that is valid until 2010 at the least," Franz said. "We are uncompromising with regard to employment protection."
Franz said workers will want to be shielded from layoffs resulting from company restructurings and will be looking for an expansion of trainee positions within the company.
Franz said criticized managers for Opel's current financial difficulties.
"They are looking too much at reducing costs and are not making important product decisions to secure the future of German production locations."
He said Opel is losing millions of euros in operating profit because its model portfolio is incomplete. The brand has neither a flagship nor an SUV, he noted.
Now that the Frontera successor will be built in South Korea, Franz said he hopes the Omega successor, the "Insignia," will remain in Germany.
But he added that the expected annual production volume of 20,000 units would only secure 200 jobs.
General Motors Europe President Carl-Peter Forster has already spoken out clearly against employment guarantees.