This thread is the first time I've really taken a look at Lexington.
It is interesting to have a near-freeway beltway, but not at all accessible to the Interstates. Maybe this is a candidate for longest isolated freeway.
Were there ever any plans to build a spur of I-64/75 to the New Circle Road in the north side of town? By my estimations, it is less than 2 miles along Newtown Pike.
Agreed on the comments with regard to BG Pkwy. It should be extended north to I-64 (and hence to I-75) or east to New Circle (to serve Lexington) or both.
Lexington needs better access to the regional highways. IMO, this means some limited highway access from the freeway part of New Circle outward to the regional highways. Three roadways would be ideal, to the west to connect to the BG Pkwy, to the north to connect to I-64/I-75 (coming from west, north, and east), and to the southeast to connect to the southern I-75. To preserve the town, there should not be any new highways that pierce the New Circle. Ideally, all of New Circle should be limited access.