Formula One world champion Lewis Hamilton was quickest for Mercedes in a rainswept final U.S. Grand Prix practice session on Saturday that was held behind closed doors due to the weather conditions.
Red Bull were talking to Volkswagen about a Formula One partnership before a diesel emissions scandal seemingly scuppered plans, said boss Christian Horner.
Renault look like having no takers for their upgraded engine in U.S. Grand Prix after Red Bull's Daniel Ricciardo said it did not look enough of a step up.