Image: Couple shopping for a new car © Tetra Images, Getty Images

Americans buy virtually everything at Costco. Eyeglasses, big-screen TVs, crates of oranges, jumbo boxes of cornflakes and giant jugs of mouthwash are stacked in the company's almost 600 warehouse stores. So why not buy a couple of tons of new car there, too?

"We are a service to the members," says Gina Paolino, the president of the Costco Auto Program, which operates as a separate division of -- and vendor to -- Costco Wholesale. Because there are about 60 million Costco members in North America, that could well include virtually everyone on the continent who is considering the purchase of a new car.

Claiming more than 1 million completed new-car purchases during the past five years, the Costco Auto Program is one of the largest buying programs around. Beyond that, because there are so many Costco members, it's one of the most generally available as well.

Of course, the Costco program isn't alone out there. Similar buying programs are offered by AAA clubs and other groups, with slight or significant differences. The AAA programs can vary from club to club around the country, and some are administered by outside vendors such as the Affinity Development Group. A company called TrueCar administers purchasing programs for USAA, American Express, Overstock.com and even Consumer Reports, among others.

How the programs recruit dealers, how they're financed and what services they offer consumers differ. For instance, though many programs are financed through dealer-paid marketing fees like Costco's, others, like at least some of TrueCar's, are paid set amounts (maybe several hundred dollars) by the dealers when sales leads turn into actual sales.

At Costco, it's almost impossible to avoid seeing the new cars placed near the entrances of most of the retailer's warehouses. They're usually mainstream models -- such as Toyota Camrys, Ford Fusions, Honda Accords or Chevrolet Malibus -- covered in signs almost begging shoppers to save money with the Costco Auto Program. And for most buyers, that's what the program would do.

Still, "most buyers" is a group that may not include you.

What Costco doesn't do

To be clear: It's impossible to buy a new car through Costco itself. The franchise laws and dealership agreements the auto industry operates under mean virtually every new car sold in America at retail must go through a dealership. Costco doesn't maintain an inventory of cars, has no agreement with manufacturers to sell any cars and can't use the leverage of its massive purchasing power to buy and/or sell cars at lower prices.

But when it comes to buying a car, the Costco program does reduce the pain.