You may ask to exempt custom-designed off-highway motorcycles that are substantially similar to highway motorcycles under the display exemption provisions of 40 CFR 86.407-78(c). Motorcycles exempt under this provision are subject to the restrictions of 40 CFR 86.407-78(c) and are considered to be motor vehicles for the purposes of this part 1051. [69 FR 2445, Jan. 15, 2004]