If you do this when shopping around for a vehicle, you do not have to worry about the dealership asking you to sign a release to pull your credit file. Make friends with the finance manager. The finance manager has more authority than he wants you to believe. Make sure you tell the dealership you do not want an inquiry on your credit report unless you purchase the vehicle from them. This will also show that you care about your credit file.
Many dealerships use the credit bureaus' scoring system only as a guideline.
For example, a secured credit card is a lot cheaper way to reestablish credit. When you buy a brand-new car with a bad credit file, your down payment can cost you more than paying cash for a clean used car would. I would start shopping for a clean used car from an individual and reestablish credit using a secured credit card. Your last resort should be the Mom and Pop used car lot where your down payment is the price they paid for the car. Trying to get Mom and Pop to put your payment history into your credit file is another story.