I tend to start thinking about getting a newer car when I have to work on it at all. With most cars going 150,000 miles before anything goes wrong or needs replaced, the upholstery and plastic and floor mats and accessories are starting to get worn, and the increased gas mileage and usability of the newer vehicle makes it worthwhile to upgrade, and not work on the old one. My current vehicles have 175,000, 134,000, 31,000, 27,000 and 18,000 miles on them. The 134,000 mile one is the only one I have worked on; it's been heavily abused with heavy loads and trailer pulling and all short trips, and has had the box replaced, seat covers replaced, floor mats replaced twice, torsion bar links, alternator, and spark plugs replaced and two sets of replacement tires. The other cars have had the oil changed and the air filters and tires replaced. One I have worked on extensively, but that's been changing it out to aftermarket performance parts. There is no joy in working on cars to me. It's a grudging necessity occasionally.