Overly birght light diving towards ground, no impact,My self and an assistant were in the car traveling north bound on the 405 freeway approaching the 710 freeway interchange. Out the front window and slightly off to the right side I noticed an extremely unusual light in the sky. I commented immediately upon seeing the light, as it was so strange and moving so very fast that I exclaimed; "WHATS THAT! " while pointing to the moving light. My Assistant saw it too.The light was not too far away as it was clear and crisp, there was no observable haze or diffused effects of atmosphere to give a sense of a greater depth or distance, the light was only about 2 or 3 miles away at the furthest I think.I think the light was about 1400 feet off the ground when I first noticed it dropping into the top of my front window's field of view. It was traveling at a very steep angle of attack ( it was diving towards the ground ) and diving at about a 45 degree angle downwards to the right. It appeared to be dropping sideways to me, not coming towards or away from me but perpendicular to my perspective.The light was traveling at an extremely fast rate of speed when we say it, It was traveling much much faster then even a commercial jet diving at full speed . We lost sight of the object at about 200-300 feet off the ground or so as it disappeared behind a small rise of trees off to our right side of the freeway so we did not get to see how it bottomed out of it's trajectory. It was traveling far too fast to "Pull Up" from the dive. As we made the gradual turn around the bend of the freeway 8 seconds later and the horizon was revealed to us on the now slightly elevated portion of the freeway we expected to see a fire ball or smoke where the object must have impacted but there was nothing to see. The total elapsed time of the streaking object must have been only 2.5 seconds total. (From about 1,400 feet elevation down to 200 feet elevation in 2.5 seconds is fast ) The object looked like a jets landing lights when they are facing you. Overly bright and it had an additional blue light on top and green accent light on the bottom, but all the time it was overly bright and cool white light looking. We also observed that it was not a warm light like a streaking meteor, or something burning up in the atmosphere, and there was no contrail or derbies field in its wake, just a overly bright cool point of light in 3 colors.