system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why are cars built with a speedometer that goes much higher than almost all legal speed limits?

I was driving my mother's car down the highway today and noticed that while the maximum set speed limit is usually 110-120 Kilometres per hour, the car itself is supposedly able to travel at 240 Kilometres per hour. As far as I am aware, it is not actually legal to travel that fast anywhere in Australia, so why are cars built with the ability to do more than twice the speed limits?
gpt
I remember this question was already answered if you search for it.  Long story short it's about engine efficiency.  You wouldn't want to push your engine to the max to reach the speed limit, it would be operating at its limits which isn't efficient.  You would want the engine to be working around 50-60% when cruising at the speed limit which most cars do.  Other factors such as engine gearing have an effect too.  That's basically a a rundown of what was the previous answer was.