With the cost of brand new minivan's costing $60,000+, I prefer to buy used ones in good condition with 90k to110k miles on them for about $5,000 from original owners who did frequent maintenance and did the timing belt recently, and then to drive them 20k miles a year (due to the long commutes myself and 3 other family members have) until they get to 250,000+ miles.
I find this more economical then the cost it would be to buy 4 new vehicles at today's prices.
These vehicles are good candidates for a high mileage oil, which treat the oil seals to help prevent oil leaks on my driveway.
Currently non of my 4 Honda Odysseys have any oil leaks as a result.
The high mileage oil also has extra phosphorous/zinc anti-wear additives, and also extra calcium (detergent).
I prefer Honda Odysseys as they have one of the lowest death's per million vehicle miles according to the Insurance Institute for highway safety in real world accidents which gets the statistics from law enforcement whenever there is a crash with fatalities.