Red Bull drivers Daniel Ricciardo and Daniil Kvyat believe the Virtual Safety Car rules need clarification following some confusion during the United States Grand Prix.
The VSC was introduced this season to avoid the deployment of the actual safety car in areas of the track where double waved yellow flags are needed.
Drivers need to adhere to a delta time on their steering wheel display during the VSC periods.
In Austin, however, both Kvyat and Ricciardo were caught out by the VSC and lost out to Mercedes rival Nico Rosberg, who overtook both despite being some five seconds behind before the VSC period.
Kvyat believes the rules need clarification as the situation is unfair.
"I think we have seen a bit of unfairness because we found that Nico, being far away from us, suddenly he was in our tail, and also because Lewis [Hamilton] because he was leading, he wasn't really following the target," said Kvyat on Thursday.
"So all the guys behind were trying to catch up. I think we'll look for clarifications from Charlie. I don't think it's a big deal. It's very easy to correct."
Ricciardo said he was overtaken by Rosberg because he was not aware that the VSC period had ended.
The Australian admitted the situation was confusing.
"I think for me... I was just confused when it was green, basically, when it was ending," Ricciardo added.
"My engineer came on the radio and said 'VSC ending' and that's normally a 10-second warning, I think.
"So I thought it was going to end soon, but then I never got any... I had to look for the boards. I didn't get anything [on my dash] in that race, so I don't know if there was an internal thing or an issue with the VSC.
"So I sort of just guessed when to go, and you look at the boards and if you don't see VSC anymore you just assume it's going. It didn't seem very clear.
"That's something we could do better. I'm sure we'll get more opinions in the drivers' briefing tomorrow.
"I know Rosberg caught us. That was already bad, I guess. And then when he passed me I didn't realise we were green basically."