We were driving from San Francisco, CA to Sacramento, CA along the I-80 E, as we were passing the I-680 interchange entering Fairfield, CA my husband Robert asked me to look at the approaching lights. He asked "What kind of plane is that?" I looked up and noticed three large, dark red circular lights pulsating in a line, one would light and fade, then the next would light and fade and then the last would light and fade. The lighting and fading of the red lights was slow and steady, but definitely in a continual linear pattern. Visible as well was one large dark green circle that was lit steadily.I said "It's just a plane", but he insisted, saying he thought it was something else, as it did not have the typical white strobes and wingtip lights common on aircraft. I continued to look as he he drove, the craft was coming directly toward us, and would pass overhead shortly.I looked up through the moonroof to see it pass directly overhead. I was amazed to see it was actually a dark grey scalene triangle shaped craft, with not only the the pulsing red and steady green lights, but with three more of the same pulsing red lights along the tail end of the triangle. I told my husband it was definitely NOT a plane-it was a TRIANGLE. It was passing approximately 500' above the freeway, and was approximately 400' long, approximately 150' wide at the wider end of the triangle. I approximate the size, but in looking through the moonroof (large size on as in an SUV) once we were directly under it, the triangle was fully visible through the moonroof and took up the entire view.I continued to watch it, but in a few seconds, it seemed to disappear, and we couldn't catch sight of it through the rear view or side view mirrors in the car. We definitely felt after seeing it that we'd seen an unidentified craft of some sort, that it was definitely not a plane. A very cool experience indeed!As a note: Robert's dad was in the US Air Force and he grew up on air bases all over the world, and has not seen an aircraft ever with those light characteristics. Robert was also in the Navy and stationed on an aircraft carrier, so he is familiar with planes and their silhouettes-both commercial and military.I am a trained scientist, with much experience technically/scientifically describing and "de-bunking" things in the name of "science". I have technical and mathematical expertise-I was skeptical about it initially but changed my mind quickly, as my eyes told me I HAD to believe what was right in front of them. We felt so strongly about this experience, we had to report it to MUFON. Thanks for all you do, keep up the good work. Information is power! We also created and have a rendered drawing of what we saw we could upload and share.