We buy new, and keep them a minimum of 10 years. Cars are so well-made these days (and our SoCal climate is so mild that rust isn’t an issue), we find we’re keeping them longer. Our current vehicles are a 2000 SUV, and a 2005 minivan.
Our oldest will start driving in a couple of years, and she’ll likely get the SUV as a first car. It’s no-frills, heavy and slow, and should be an ideal first car for a young driver. At that point, we’ll buy a new vehicle for DW, and will be a 3 vehicle family.
The van is the best overall vehicle we’ve ever owned. It’s at 175K miles, and still runs great. Barring any huge repair bills, we’ll likely keep it until both kids are off to college. So we’ll probably end up getting 20 years out of each of our current vehicles. DW wants a Toyota pickup as her next vehicle. Based on reputation, that should easily go 20 years, too. Geez, if we don’t change something in our buying habits, I probably only have a couple of new cars left!