Hockenheim - The debate about the cockpit protection concept 'halo' continues to rage at Hockenheim.
GPDA president Alex Wurz is furious that the teams voted to delay it until 2018, arguing that all the drivers signed a document unanimously supporting an immediate debut.
Nico Hulkenberg told Germany's Auto Motor und Sport: "I didn't sign anything."
Delayed until 2018
Red Bull's Dr Helmut Marko agreed: "Our drivers didn't either."
It was rumoured that Bernie Ecclestone might have moved to appease angry drivers by saying that after tests at Spa and Monza, a 2017 halo debut might be back on the cards.
But Hulkenberg said: "You can't change everything again in September. The engineers are now flat out designing the 2017 cars without Halo."
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He thinks a delay until 2018 is the best idea.
The Force India driver said: "There are too many scenarios that are unknown, so it's good that we're going to test it more."
Drivers must decide
Mercedes team chairman Niki Lauda agrees: "Let all the drivers test it and we'll see what they say. We really don't know if there are visibility problems on certain corners with at certain tracks."
Red Bull's Marko, meanwhile, criticised the recent FIA presentation about Halo that changed the mind of world champion Lewis Hamilton.
Marko said: "Certain accident scenarios were not even mentioned."