So the rule is the motor, drive train and body need to survive 300,000 miles? Then there is the problem of deer hits and vehicle accidents. Then the problem of getting tired of it in 10-15 years and selling it or trading it in and the new owner does no further maintenance.
Speaking of maintenance there is the story of grandpa's axe. He had the same axe for 60 years. Sharpened it regularly and oiled the handle. He also replaced the head a few times and the handle two or three times, but it was still grandpa's axe.

But seriously if you want a vehicle to last 300,00 miles you have to ignore " the repair is worth more than the vehicle" That is what causes the end of most vehicles.