Force India team principal Vijay Mallya has expressed his opposition to customer cars, and says there are still many questions to be answered about how the concept would work.
Mallya says that the cost issue is unclear, and that it would be impossible for a customer car to be as competitive as a works machine.
"I have never supported the concept of customer cars," Mallya told Motorsport.com.
"If the big four who control the majority of the Strategy Group are going to virtually drive out the small independent teams and then fill up the grid with their own customer cars it remains to be seen how attractive it will be to the audience, what the costs will actually turn out to be, and more importantly how can a customer car be as competitive as a constructor's car?
"What about upgrades? What about the time lag in delivering upgrades to the customer? There are so many pending issues which people don't seem to examine in detail.
"There's just one sweeping statement, 'customer cars,' with a view to perhaps answering the inevitable question, which is if the small teams disappear, how do you fill the grid?"
Strategy Group useless
Mallya is adamant that the Strategy Group is not working, and says that the big teams are simply looking after their own interests.
"The Strategy Group is nothing but the four big teams deciding the way that the sport has to move forward," he added.
"And everybody is protective of their own corner, their own interest, and that's it. One has to just learn to live with this situation, however unacceptable or impractical it may be.
"There are meetings that don't produce any results, no cost cutting measures, nothing that will really seriously address the sustainability of F1.
"So until the big four teams take responsibility for the sport as a whole, as long as they continue to guard their own corners, nothing's going to happen."