If you plan to keep it 10+ yrs buy new.
Your advice was good in the 1970’s. It’s no longer appropriate. Car last forever now. In 2009, I bought a 2006 Pontiac Vibe with 145,000 miles. I sold it about 3 years ago with 300,000 miles. The original clutch started to slip. The most expensive shop repair was $95. Brakes, tires etc. was the only maintenance.
My wife drives a 2015 Chevy Equinox. We just did about $800 in tires and suspension work. For a car we paid off years ago, I’m not complaining. At 120,000 miles, I just replaced the original battery this week.
Cars should easily go 200-300,000 miles with just normal maintenance. It makes little sense to buy new.