  A classification of extremal double circulant self-dual codes of lengths up
to $88$ is known. We give a classification of extremal double circulant
self-dual codes of lengths $90,92,94$ and $96$. We also classify double
circulant self-dual codes with parameters $[90,45,14]$ and $[96,48,16]$. In
addition, we demonstrate that no double circulant self-dual $[90,45,14]$ code
has an extremal self-dual neighbor, and no double circulant self-dual
$[96,45,16]$ code has a self-dual neighbor with minimum weight at least $18$.
