Speedy Black Triangle over Central California in the middle of the day.

I was traveling west on I-80 near Davis with my mother mid-day.  We both saw a black triangular shaped aircraft to the south of us by several miles.  I think we had a side view of it because it absolutely had a front end that came to a definitive point and more mass toward the rear where it was thicker.  It was hard to gauge it's size at that distance.
The object began its path below where we could see because of a berm built up on the side of the highway so we couldn't tell if it started on the ground or not.  It shot up in a perfectly straight line at about a 45 degree angle from behind the berm.  It moved at incredible speed until it got up a couple thousand feet and then just stopped dead in place below some low level clouds.  It rotated in place so the front end was pointing straight up, and then shot up through the clouds at the same incredible velocity.
I'm very knowledgeable about military aircraft, and this was not only moving with "linear" speed (unlike aircraft with throttle) that far exceed conventional aircraft, it stopped in place so abruptly that any pilot would have been killed.
Date may be approximate.  PD