The big expenses in life, IMHO, are interest payments (mortgage, car, boat loan interest), depreciation, and the cost of raising and educating kids.
Whilst you can make savings on day to day living expenses such as food, the savings on those things will pale into insignificance compared with interest, depreciation and the cost of kids.
So, for many years, I have been taking the long view approach to buying and keeping cars for as many years as they are safe to drive, saving to pay cash for my cars and boat, and teaching my adult kids, who would like cash hand-outs from time to time, the concept that I learnt in the book, "The Millionaire Next Door", to not make my kids into "economic outpatients". That is, once they have all grown up and have established their independent lives, they are truly on their own financially.
Whilst the cost of a gallon of fuel irritates, that is the small cost in running a car each year - the big cost is depreciation.
My wife and I are thrifty on many of our daily living costs but in truth, the savings made on those are inconsequential to our standard of living - which is very good.
By getting the big expenses of interest, depreciation and raising kids in control, and living within my means and saving the surplus, I am now very comfortable in retirement several years ahead of my original life's expectations as to when I would retire.
As an afterthought, I have also minimised transactional costs pretty well by living in the same house for 25 years and not trading in the old wife at any time over the past 32 years. (After all, she was the best that I could get with the car that I had!)