I doubt if we will resolve the biggest American production car issue here. In passing, at a local Mopar show a guy brought in an enormous Chrysler sedan which was way longer than my 58. It was from the late 70s, I think. But, more to the point, which is the biggest Imperial? I guess there could be a variety of ways to consider this. There is length, width, height and weight to be considered. I imagine the predominate statistic would be length, but the others are not insignificant. I would not be surprised if the winner came from the 1920s. Some of dem cars was big. Hugh