"Optimized" means a good balance of variety of factors. Max speed would save the most time, but with total disregard to safety, mpg, engine longevity, etc. Driving at max speed would be opposite of optimum. From a practical standpoint, cruising at 80 where speed limit is also 80 gives a good balance between mpg and time. Since on an 80 mph speed limit section of a highway, most traffic moves at or near 80, cruising at the same speed as all other vehicles would maximize the safety for everyone.Then, you'd have to say maximum speed is the "most optimized" speed, as time is more valuable than fuel, or tickets, or the increase in insurance from paying for those tickets as well as burning more fuel. Then, there is also the safety aspect of higher speeds and the greater chance of wasting time recovering from more violent crashes, or, even the chances of using up all your available time if you die in one of those more violent crashes....
OR, we could stay on topic and discuss the 9th generation Honda Accord MPG and "optimized" speed, and we get back to a topic we can actually discuss from a practical standpoint, which is: the Accord MPG value is certainly not "optimized" for maximal MPG at 80 mph.