It's one of the toughest decisionscar owners face—fix up the old caror spring for a new (or newer)one. A study commissioned by autoparts dealer Auto Zone reveals thatthe cost of repairing the old car isthe key, and that the tipping pointfor the average consumer is$2668. Any estimate higher thanthat, and the old car should be history.A breakdown of the numbersshows that more than 80% of consumerswould put the car up for saleif the repair estimate topped $1000,although for 53% it would take anestimate of $2000 or higher to triggera hunt for a new car. Still, mostconsumers, about 82%, said theywould prefer to repair the car if theycould afford to rather than get anew one. According to the AmericanAutomobile Association, theaverage cost of a new car nowapproaches $20,000; an averageused car is about $9000.