I think i posted a thread about this in a different topic, but again I recommend doing all your research before going to any dealership. Some common sites are www.kbb.com
, edmunds.com, www.cars.com
, etc...With Mazda3 there is a college grad rebate of 500 bucks. And sometimes a 1500 MAC rebate if you finace with Mazda3. The dealership has three main sources to make a profit.
1) The selling price of the car - not sure if "invoice" price is really the invoice, but from all the dealerships I went to I was either offered a little below invoice or a little above invoice. The dealship still gets incentives from the factory for keeping the cars rolling off of their lots with bonuses, factory priority, etc...so they can and will sell the car below or at invoice.
2) Car trade in - If you got a good deal on price then becareful for the next two. Car dealers usually don't offer a fair deal on your trade-in. They will give you a ridiculous quote the first time and slowly increase it to make it seem like you are winning. Example I reserached my trade in on kbb.com to be around 3000~3500. The first dealer offered 2000, after I stood up to leave...they magically increased it a little by little to 2,800. I was still expecting at least 3000 considering my car was in good condition.
3) This last step is the main way a dealership will make their money. In the finace office. Since most people don't have 18,000 to pay cash down they will finace a car over 4 or 5 years. I'm not sure how they calculate the interest but it's surprising how much difference 4% and 6% will make on your total payments. I think I was offered 6.98% at the first dealership and calculating my total payments over the 4 years I was paying more than 2500 over the MSRP. The second dealership gave me 4.69% and after establishing a good payment history I can refinace after a year and get a lower APR. This is where they will offer BS add-on and some may be real and others simply wrong. They will also try to sell you protection coverages and other maintenance packages etc...If you have insurance (which is required to have by law) you don't need their xtra protection coverages.
In summary please do all your research, go to at least 3 different dealerships. Usually dealerships in busy locations like right near a busy high traffic highway will give bad deals simply because they can sell to a lot of uneducated customers that are first time walk-ins. Usually dealerships in smaller cities or near country areas will give you better deals and will make it worth a drive out there simply because they don't get as much customer traffic, they will work harder to make their sale and maintain good reputation.