best new car warranty are the: 1  Lexus Warranty 4yr/50k mile bumper to bumper. ( 2 T3) Cadillac Warranty 4yr/50k mile bumper to bumper. ( 3 T3) Buick Warranty 4yr/50k mile bumper to bumper. ( T2) Mitsubishi Warranty 5yr/60k mile bumper to 1  bumper. (T2) Kia Warranty 5yr/60k mile bumper to bumper. ( T2) Hyundai Warranty 5yr/60k mile bumper to bumper.