Back in 1989, my father came up with a formula for buying a vehicle.
For every $100 you spend, the vehicle should go 3,000 miles.
Our 1993 Mercury Villager did this tonight. (woohoo!) It actually met the formula many moons ago for two reasons. #1 Inflation. The formula can now be adjusted to 3,000 miles for every $170 you spend. #2 It has a sticky odometer. Two years ago we noticed it was at 162,512. On the way back from Florida, it still read 162,512 miles. We know how to fix this, but we sometimes forget to push the little button that reminds it to keep counting.
It's a good van. It's served us well. I think I want a new one in the summer. Something with two sliding doors, a rear windshield wiper that does not have a mind of its own, turn signals that work after using the hazard lights and all cruise control options operating rather than only 1/3, 40% of the time. Leather seats would be nice too, but I don't want to be too picky.
ps. In case you do not want to crunch the numbers, it is not easy for a vehicle to "make formula." Only a handful have done so in the last 20 years.