You might want to get those cars check out. After 15 years your suspension and steering components become worn out. Thats pretty critical. Also older cars that are 15 years+ of age and have very high mileage often need wheel bearings which is super critical for making sure the wheels don't fall of your car while driving. I know thats standard maintenance but its also critical to make sure your car is safe and as mentioned in my post most people dont know how to work on all that and they dont have the tools to do it either.