Why are the majority of cars able to drive nearly double the maximum speed limit of most countries?

Question

Why are the majority of cars able to drive nearly double the maximum speed limit of most countries?

In: 8

Answer 1

Cars need to be capable of low gear, high RPM operation for driving up gradients. They also need to do low RPM, high gear operation for efficient fuel use at higher speeds.

Therefore, they can also do high RPM, high gear driving, which means the top speed is well above their designed optimum efficiency speed range.

Edit: Due to a number of similar replies, I’m talking here purely in terms of the mechanical reason that road cars *can* achieve such high speeds, not whether they *should* or not.

Edit 2: A [simpler version](https://www.reddit.com/r/explainlikeimfive/comments/vqdqwh/eli5_why_are_the_majority_of_cars_able_to_drive/ieqw5xq?utm_medium=android_app&utm_source=share&context=3) for those that need it. I’ve tried to remove any big words.