(Image credit: Getty Images) You may have heard that taking a defensive driving course — sometimes called a driver improvement course or something similar — may lead to car insurance discounts. But you might not know that some states actually require insurers to offer those discounts. You also might not know just how affordable the courses are and how big of a discount you can get for taking one. Most eligible courses can be done completely online and take just four to eight hours to finish. Often, insurers will keep the discount in place for three years after the date the course was completed. At that point, you can simply take the course again to get the discount for another three years. Let's say you're paying $2,697 per year, the current national average cost of car insurance , and after taking the course, you get a 5% discount (the low end of what most states below mandate). That means you'd save a little over $130. Many of the eligible online courses I found (and linked to below) cost around $25.…