The ornamental design for an autotransporttrailer, as shown and described.
FIG. 1 is a top perspective view of an auto transport trailer in a lowered position;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof, the right side being a mirror image;
FIG. 5 is a top view thereof;
FIG. 6 is a top perspective view of the auto transport trailer in a raised position;
FIG. 7 is a front view thereof;
FIG. 8 is a rear view thereof;
FIG. 9 is a left side view thereof, the right side being a mirror image; and,
FIG. 10 is a top view thereof.
The broken line showing of the auto transport trailer is for the purpose of illustrating portions of the article and forms no part of the claimed design. All sides not shown form no part of the claimed design.