Getting a written estimate for a repair ahead of time will give you a general sense of what it will cost, said David Bennett, a manager of repair systems at AAA. You can also require the mechanic to contact you and get your approval if the repair cost exceeds the estimate by a pre-specified amount, Bennett added.You want to make sure the technicians who are working on your car are certified to work on the part of your vehicle that is being repaired, Bennett said. Read more: This $8 million Lamborghini seized from an African dictator's son just became the most expensive ever soldUnderstanding the repair shop's hourly labor rate can give you some insight into your total repair costs, Bennett said.Most repair facilities offer warranties of 12 months or 12,000 miles, Bennett said, though AAA-approved facilities offer warranties of 24 months or 24,000 miles. See also: Apply here to attend IGNITION: Transportation, an event focused on the future of transportation, in San Francisco on October 22The time it takes to repair a vehicle can vary widely depending on the nature of the work being done, said Karl Brauer, the executive publisher of the automotive shopping and research sites Autotrader and Kelley Blue Book, so it can help to do research ahead of time.