For years, Adrienne De Forrest, a member of Boulder (Colo.) Mennonite Church, had driven a 1991 Subaru station wagon that now had over 250,000 miles on the odometer. The car had been reliable and the engine was strong, but some peripherals were starting to go bad due to age and weathering. Aware that she might have to replace the car sometime, she researched dealers’ prices for used cars and put away enough money to cover the cost if it came to that …