Daniil Kvyat says it is time for actions rather than words from Renault as Red Bull continues to trail Formula 1's frontrunners.
Red Bull and Renault became locked in a war of words amid a tumultuous start to the season beset by performance and reliability issues.
Kvyat fears that his team has slipped back since the Australian Grand Prix, and made it clear that assurances from Renault over steps forward were no longer sufficient.
"I think we don't want any promises: we just want to see the progress itself," explained the Russian, who has just two ninth-placed finishes to his name this season.
"Both as a team and on the engine side, we all want to improve.
"That means working with Renault, working with the chassis, me as well, working out where I can pick up the pace.
"It is a long process and hopefully we will come up with something."
Kvyat said that Red Bull was working on a big update for the next race in Spain, which he felt was vital if the Milton Keynes outfit was going to start challenging nearer the front.
"We plan some [upgrades], like many other teams," he explained.
"Hopefully it will work well, and I am confident that the team is going to move forwards from now on because we have been going backwards."