My general rule is if I have spent more in the past 7 months on repairs (not normal maintenance) for the car than I would have put out for that same time period for monthly payments on a reliable car, it is time to get a new one. At this time, you would probably have to pay about $300-350 a month for a reliable car. If you spent more than $2200 on repairs in the past 7 months, it is time for a new car.