Driving north on Hwy 16 ten miles south of Fredericksburg, TX. Westbound enroute aircraft at cruising altitude with con-trail caught my eye at 12 o'clock high. Extremely bright object approx same azimuth as aircraft appeared at 10 o'clock. I thought sunlight reflection from another aircraft. Being a retired Air Traffic Controller, I was watching for "separation" however determined it's altitude to be much lower than the enroute aircraft. It also became apparent the object was not moving and it was much too bright to be an aircraft. I watched as much as I could, as I was driving 70+, and the object remained stationary. I could begin to make out it's shape and detail as it became brighter - vertical cylinder with cone-shaped ends. The ends may have consisted of more than just the cones - as if the frame (?) of the cylinder continued to extend to a similar length as the end-cones. The color was first an extrememly shiny silver then became increasingly brighter white and somewhat yellowish until I could no longer make out the shape of the object. It was as bright as the sun. So bright I could not look at it any longer. Then it was gone. Whole event lasted approx three minutes. I observed it for a total of 20 seconds while driving.Estimated altitude - 1500 to 8000 AGLEstimated distance - 3 to 10 milesEstimated size to be that of a G4 to F-28 at 3 to 5 miles distance - length / wingspan (vertical). Perhaps 50 feet longer.Although the direction of this object was towards the town of Fredericksburg and the Fredericksburg airport, I passed the airport within minutes and was watching the entire time for local air traffic but did not observe any. No aircraft moving on ground and none in the air. Being a retired Air Traffic Controller, and having worked at some of the busiest airports in the country, my eyes are trained to spot hard-to-see aircraft and I have seen aircraft and weather baloons in every imaginable flying configuration. I can assure you this object was neither and it was also too bright - as bright as the sun before it disappeared. I wasn't going to report this until I saw another event reported in San Antonio the day before. Thought you might want to know. Thanks.