June 15 : Audi have blamed airborne gravel for Formula One driver Nico Hulkenberg's Barcelona-Catalunya Grand Prix retirement. The German veteran coasted into the pit lane and retired from Sunday's race when his car suddenly lost power. The team later revealed it had nothing to do with reliability, with Hulkenberg saying stones thrown up by Liam Lawson's Racing Bulls car had hit an emergency electrical cutoff switch on the Audi behind. "Liam ran slightly wide ahead of me and put a wheel into