Scroll through the spec sheet of almost any European performance car and one number keeps appearing with suspicious regularity: 155 mph. It doesn’t matter whether it’s a BMW sport sedan, a hot SUV, or a high-powered wagon — that ceiling shows up again and again. Far from a coincidence, it’s one of the most deliberate and enduring unwritten rules in the automotive world. But where did it come from, who decided on it, and does the reasoning still hold up today? We dug into the history to find out.
