Which came first, the chicken or the egg?
About 40 years ago I discovered that having to depreciate our new and newer cars every year was having a major negative effect on our family's Net Worth. [I have calculated our family's Net Worth every January 1 since about 1980.] So I stopped buying new cars and started buying and then keeping good quality cars for as long as they're rust free and reliable - which is about 20 years.
I have to think that simple idea has had a big effect on our family's accumulating wealth.
All that to say, driving older cars may be one of the reasons your friend is wealthy.