ON 11/23/2018, I WAS DRIVING WESTBOUND DOWN A HILL IN THE INSIDE LANE OF A HIGHWAY IN LIGHT DRIZZLE, SPEED APPROXIMATELY 50 MPH. THE HIGHWAY WAS WET BUT NO STANDING WATER. SUDDENLY THE FRONT WHEELS BEGAN ALTERNATELY PULLING TO THE LEFT, THEN RIGHT, THEN LEFT, THEN RIGHT, CAUSING THE VEHICLE TO WEAVE UNCONTROLLABLY. AFTER JUST A FEW SECONDS THE CAR SWERVED ACROSS THE RIGHT LANE, SPINNING TO FACE THE WESTBOUND TRAFFIC. THE CAR THEN SWUNG UP AN EMBANKMENT ALONG THE ROADSIDE, SKIDDED BACKWARDS ON ITS LEFT SIDE, THEN CAME TO REST ON THE RIGHT SHOULDER OF HIGHWAY, STILL FACING THE WESTBOUND TRAFFIC. IN A FEW MINUTES, HIGHWAY PATROL ARRIVED, AND A PATROLMAN BACKED THE CAR DOWN THE HILL ABOUT 200 YARDS TO AN EXIT. AS HE WAS BACKING, THE FRONT END AGAIN WAS WEAVING FROM SIDE TO SIDE. I DON'T KNOW WHAT IT WAS THAT HAPPENED, BUT IT DID NOT BEGIN WITH APPLYING BRAKES OR SKIDDING ON THE WET SURFACE.