The warning is about Ambient Auto Centre, which has been advertising high-end, late model vehicles on several Canadian websites at prices well below normal.
The catch, according to Canadian and American regulators, is that Ambient doesn't appear to exist much beyond having an elaborate website.
"It's just a complete scam," John Cobb, an investigator with the Oklahoma Used Motor Vehicle and Parts Commission, said Wednesday.
"They're trying to get a victim on the hook to wire them the money for a vehicle."
The company promises to ship the vehicle, but Cobb said that won't happen and the buyer would simply be out of any money sent.
The Canadian sites on which Ambient advertises include Autotrader, Wheels, eBay, Craigslist, Kijiji and Autocatch.
In an interview from Oklahoma City, Cobb said the scam appears to be aimed solely north of the U.S. border, and inquiries about Ambient have come in from across Canada.
"As far as I can tell, they're just targeting Canadians," Cobb said.
"I haven't had anybody report this dealership from anywhere outside Canada."
The FBI has refused to get involved because there are no known victims of the scam at this point.
Ambient's website boasts of the "largest selection of used luxury cars" but photographs of vehicles appear to have been ripped off from other car dealers, and customer testimonials appear to be fabricated, regulators said.
A call to the number listed on Ambient's website went to an answering machine Wednesday and no one returned a voice message seeking comment.
Consumer inquiries about Ambient began coming in to Cobb's office in mid-October. When he couldn't find a licensed dealer in Oklahoma by that name, he went to visit the dealership at the listed address.
"It turns out to be an empty field. That was a red flag right there."
In the following weeks, the number of calls picked up.
Cobb said he was able to track the company's bank account to Georgia and their website registration to Los Angeles.
"It's kind of all over the place," he said.
Terry O'Keefe, with the Ontario Motor Vehicle Industry Council, warned consumers to take extra precautions when buying a vehicle online and notes they may have no recourse if the great deal turns out to have been too good to be true.
For one thing, O'Keefe said, it's imperative to confirm the seller's identity. Call to find out if the dealership is licensed, and, if possible, go see the vehicle or have someone trustworthy do so on your behalf.
"You've got to do research, research, research," O'Keefe said.