VEHICLE WAS AT 109500 MILES, OIL CHANGE 6 MONTHS PRIOR AND DUE FOR OIL CHANGE AT 110000 MILES. NO IRREGULAR NOISES AND NO WARNING LIGHTS. WAS DRIVING IN THE CITY FOR ABOUT 5 MINUTES AND ON HIGHWAY FOR FIVE MORE MINUTES. NOTICED BURNING SMELL IN CITY BUT WAS BEHIND A TRUCK AND DISMISSED IT AS THERE WERE NO SIGNS OF PROBLEMS IN MY CAR. ABOUT FIVE MINUTES LATER, ON I-90 EB IN MT BAKER TUNNEL, NOTICED FLAMES COMING OUT OF THE FRONT LEFT HOOD. PULLED OVER AND CALLED 911. WSDOT RESPONDED TO INCIDENT, AND GEICO DEEMED CAR A TOTAL LOSS. NISSAN SENT INSPECTOR WHO SAID THEY DID NOT FIND MANUFACTURER DEFECT. GEICO INSPECTOR SAID THEY COULD NOT DETERMINE THE CAUSE OF THE FIRE DUE TO EXTENT OF DAMAGE.