There's a number of common problems, mostly with the generators and wheel bearings, (if the car has anti-lock brakes), but those have nothing to do with high mileage. To prevent repeat generator failures, replace the battery when it gets to be around two years old. Engines and transmissions today can go a real long time. The failures that do occur aren't typically related to mileage. What high mileage IS good for is negotiating a lower price when buying the car.