DETROIT (AP) -- Buick tied with Lexus as the highest-ranking brand in a closely watched study of vehicle dependability, marking the first time in 12 years that Lexus has shared the top award, J.D. Power and Associates said Thursday. Cadillac, Mercury and Honda rounded out the top five brands in the annual survey, which measures problems experienced by the original owners of three-year-old vehicles. Both Buick and Lexus had 145 problems per 100 vehicles. The worst-performing brand, Land Rover, had 398 problems. The industry average was 216 problems, down from 227 problems in last year's survey.