My current commute is about 50 miles each way. 2/3 of the trip is 45-55 zone. I reduced my cruise speed from 68-62 mph. Only changed my commute time by a couple of imperceptible minutes, but increased my fuel economy by at least 10%! 42 mpg on the last fill up and that included 30 minutes of heavy traffic and red lights.
Previously, I ate at the cafeteria every day and often stopped for snacks and drinks on the way home. Last month was over $200 for this expense although that is higher than usual. This month, I have spent $0 so far.
Wife has a significant commute as well, and she was taking the turnpike most of the time, which costs us $125/month in tolls. This month she has cut back most of her turnpike usage.
Some big savings all in all.