Except as otherwise provided in this section, the Traffic Infractions and Uniform Fine Schedule adopted by the Supreme Court for prepayment of fines shall, in all instances where prepayment of a fine is permitted, include a fine of $6 per mile-per-hour in excess of posted speed limits provided for in this article. However, such Traffic Infractions and Uniform Fine Schedule shall include a fine of $7 per mile-per-hour in excess of posted speed limits for a violation of §§ 46.2-873 and 46.2-878.1 and $8 per mile-per-hour in excess of posted speed limits for a violation of § 46.2-878.2. Any person who drives a motor vehicle at a speed in excess of 80 miles per hour but below 86 miles per hour on any highway in the Commonwealth having a maximum speed limit of 65 miles per hour shall be subject to an additional fine of $100.