Notarian nailed it in his description. My very favorite road in this part of California. The pavement is remarkably good, and the road snakes up and over and down a low but steep mountain pass. Great views at the top. Hit it early in the morning if you have a chance, while it's still quiet. I'll post a some video taken by a friend on ride we did together.
Tepusquet Rd is 18 miles of twisty, undulating and newly laid, superb tarmac. From the south, the road begins as 2 lanes and meanders past a few ranches before changing to a wide-ish single track and leaves civilization behind for the next 15 miles. The definitive back road in the area.
It connects with Foxen Canyon Road at the south end and together make for a brilliant ride representing much of the back-country roads around Santa Maria - San Ynez.
However, Foxen Canyon road surface is 3 star with more traffic and many wine/vineyards and by far the route to/from San Ynez Valley.