Should I repair or simply replace my old car?

When I was a child, I remember my Dad telling me: “When a vehicle has 100,000 miles (160,000km) on her, trade her off because she has reached the end of her life!”. I am not sure why he always referred to his vehicles in the feminine form; but for my Dad, the truck was always a “she”. I look back on his comment now with amusement because I don’t even consider a vehicle to be “used” until it has at least 300,000 km on it and occasionally see vehicles with 500,000 km on the odometer. Better manufacturing, better materials, better roads, and especially better oils have resulted in vehicles lasting longer than ever before.