GOING 45-50MPH ON DRY ROAD WHEN VEHICLE HIT GRAVEL, STARTED SWERVING LEFT/RIGHT; HAD NO CONTROL; APPLIED ABS BRAKES TO STOP SWERVING; WENT DOWN AN EMBANKMENT & HIT TREE; AIR BAGS DID NOT DEPLOY. VEHICLE ROLLED 2 TIMES 7 LANDED ON ROOF. HAD SEAT BELT ON. VEHICLE TOTALED. *AK