Just remembered to check the seat bolts on my car, busy day sorry.
I have found a bit that WILL fit the seat bolts but I do not have a fully set of them, only a few sizes.
In the first picture, I have placed the driver socket into the seat bolt.
The second picture is the same socket drive, left on the front seat for info.
It is a square 3/8"AF drive in the head of the socket.
The size used to fit the seat bolts, is a x8mm "T-Star" ( torx ) I do believe.
It is similar to the std torx male spline, but there appears to less gripping splines on the "T-Star" drive bits, as seen in my picture two.
Hope this answers the question posted.