When a vehicle gets older and starts requiring more frequent, expensive repairs, it can be difficult to decide whether to keep maintaining it or trade it in for a new one. There are different opinions on when a car is no longer worth repairing, but there are some general rules of thumb. If a major repair will cost more than half of the car's value, or if the car has become unreliable to the point of putting you in unsafe situations, it may be time to trade up.