Sounds like it's from a car dealership.
If it is, you're probably "pre-approved" because you are in the phone book! LOL.
That is strictly a marketing ploy they use to get you in the dealership. A mass bulk rate mailing to thousands of people. If it's from a dealership, I immediately toss it.
If it's from a CCC, I will look at and think about it. You met their preliminary criteria(perhaps by only getting your credit score from the CRA's, maybe). Only AFTER you call them, or mail it in, they then pull a hard inq on you, as you've given them permission to do so. In essence, a "pre-approval" letter is only an advertisement.
Hope that helps.