I PURCHASED A 2010 JAGUAR XF LAST SUMMER AND BELIEVE THERE IS A SERIOUS SAFETY ISSUE. SHORTLY AFTER TAKING DELIVERY, THE POWER BRAKE ASSIST FAILED WHEN I WAS ENTERING A FREEWAY. FORTUNATELY, I HAD TAPPED ON THE BRAKES TO AVOID A CAR IN THE LANE I WAS ENTERING. I IMMEDIATELY REALIZED THERE WAS VERY LITTLE BRAKING POWER. IF I HAD NEEDED TO BRAKE AT A HIGHER SPEED ON THE FREEWAY, IT COULD HAVE BEEN DISASTROUS. THE SERIOUS ISSUE IS THAT THIS FAILURE DOES NOT TRIGGER A 'BRAKE FAILURE' LIGHT ON THE INSTRUMENT PANEL. THEREFORE NO WARNING. I LIMPED HOME AND HAD THE CAR TOWED TO THE LOCAL DEALER. THE PROBLEM WAS THAT A PLASTIC TUBE WHICH CARRIES THE ENGINE VACUUM SIGNAL TO THE BRAKE UNIT HAD BECOME DETACHED, THUS NO POWER ASSIST FOR THE BRAKES. THE DEALER REPLACED THE PLASTIC TUBE. I CONTACTED JAGUAR HEADQUARTERS TO INQUIRE ABOUT A BRAKE FAILURE WARNING ALARM FIX FOR THIS PROBLEM, BUT THEY INFORMED ME THAT 'THIS WAS WAY IT WAS DESIGNED. NO FIX POSSIBLE.' *TR