Most of the time going over the speed limit and getting caught is going to cost you time and money. But there are some instances where speeding is actually legal.

Before you get your hopes up about some abstract wording in a law book somewhere that allows you to speed and be as reckless as you want, this doesn't exist. But in some states there are exceptions that allow someone to speed in certain cases.

Some states actually allow cars to go up to 5 miles over the speed limit and won't give out a speeding ticket. But you can still get pulled over to be given a warning about your speed.

Some states have a speeding while passing exception. If you are on a two lane road and want to pass someone going 5 under the speed limit, it's going to take awhile to pass if you only go the speed limit. These states recognize that speeding to get around the car is actually safer than being in the lane with oncoming traffic for a long period of time.

Some states allow a car to drive with discretion especially when alone meaning that one could be speeding while still driving safely.

Knowing your local laws is what is most important. It's difficult to cite every place in every state that has speeding exceptions because their are too many. Find out your local driving laws so you know what is and is not legal to avoid problems.

Knowing the laws in your jurisdiction can also help you fight a speeding ticket if you get one because you know what has to be proven to find you guilty. You never know what kind of exceptions might be found to prove your innocence according to the law.