I was 30 before I bought a car and drove regularly. I lived in an urban area, close to work, had a crappy income, but was able to save a lot of money. A group of us took turns renting a car quarterly for getting to a Sam’s Club, outlet mall shopping, taking a day trip etc. Timing it correctly, rental specials made this really attractive.
As we moved on with life, got better jobs, homes in the suburbs, etc. we bought cars. I knew a few couples that kept to one car.
Depending on how you live, this can be a huge money saver for some one that is young.
I boosted the power/efficiency of my car:
Replace paper air filter with K&N re-usable = > mpg
Replace factory muffler with high-perf = > mpg
Mobil 1 oil and extra-long life filter = > mpg
Performance rims and tires (50psi) = > mpg
Remove backseats for less weight = > mpg
Insulate air intake (cooler air has more oxygen)
Manual trans. = 10% more power/efficiency
So there are steps the avg. person can take to improve mpg and hp. My PT with a 5-speed can smoke the tires off with only the above mods.