Imagine this ... You're ready to buy a new car. You've done your research on the web at a site like Edmunds.com so you know what the dealer has paid for the model you want. Based on your information you've established your comfort zone for price haggling.

You walk into the dealership, meet with a salesperson, and begin negotiations. At the end of your test drive and haggling, you're confident that you've made the best deal possible. No way you're getting ripped off because this time you are an "informed consumer" unlike when you bought your last vehicle.

One final step stands between you and your brand new "ride" - financing. Your credit is outstanding so you get what you believe is the lowest possible interest rate from the dealership. You drive away in your shiny new vehicle triumphant!

Ready for a dose of reality? According to a new study, there's a 1 in 4 chance that you've been "taken for a ride" by the dealer's finance department, especially if you are female or a minority, by as much as an extra $1,000.

The Consumer Federation of America, a Washington, D.C.,-based consumer interest group, said consumers often pay additional fees in that process - totaling as much as $1 billion nationwide - without realizing they qualified for cheaper financing.

Here's what can happen behind the scenes: a bank approves an interest rate, the dealer tacks on additional percentage points as a kind of service fee and then the dealer and lender split the difference.

To be fair, not every dealer is guilty of this markup. However, enough are involved that many states are now considering new "truth in advertising" lending laws. New laws would require auto dealers to inform customers of the original rate offered by the bank and what the dealer is offering to the customer, after tacking on their additional finance fee.

Shopping around with your bank, credit union or the internet can help you to find the interest rate that you qualify for in a loan. Remember, the auto dealer is in business to sell cars, not to offer loans.

The next time you're in the market for a car, don't just research the model, make, and add-ons. Research fair interest rates as well so that you'll know if you're getting the best rate possible from the auto dealer or if you're being "taken for a ride."