Force India are reportedly considering halting their car development programme for 2016 in order to focus on preparing for next year's new rules.
The Silverstone-based team's founder and boss Vijay Mallya has been missing from the paddocks so far this year amid his financial and legal troubles in India.
Force India and Sauber are pursuing Formula 1 through the European Commission over the sport's governance and income systems, and are reportedly unhappy with what Christian Horner last week called the "weak" new engine rules.
"I think we'll reserve our position," said deputy boss Bob Fernley, who is believed to have written a letter to the FIA to voice the team's displeasure.
While Sauber was absent from the Barcelona test this week, Force India in Spain pushed ahead with a significant car upgrade.
"It reminds me of the debut of our B-car last year," Nico Hulkenberg told Auto Motor und Sport. "It feels very different."
It is believed that Force India designed the upgrade to be a strong basis for the remainder of the season, as the teams with the smallest budgets will struggle to run parallel development programmes for 2016 as well as the big changes coming next year.
"It looks as though we have a lot of potential in this package," said technical boss Andy Green. "We can find a lot of laptime through the setup.
"Perhaps we will then only improve the car with small, detailed steps."
If that sort of plan is replicated by the other midfield teams like Toro Rosso and Haas, it is good news for the bigger-budgeted McLaren-Honda.
"We hope that we can beat the midfield through our pace of development," confirmed McLaren boss Eric Boullier.
McLaren supremo Ron Dennis even warned last week that two teams appeared in danger of complete collapse.
"Certain teams are currently experiencing hardship, and in fact I wouldn't be too surprised if one or two of those teams fail to make it to the end of the season," he told F1 Racing magazine.
The 2016 championship continues next weekend with the Monaco Grand Prix.
