Sources close to Floyd tell us he's in the hunt to purchase a 2009 Maybach 62S Landaulet -- which features a V12 Twin Turbo Engine with 620 horsepower.

The owner of the car is famed high-end car dealer Obi Okeke -- aka Dr. Bugatti -- who tells TMZ Sports his ride is one of only 8 ever produced in the world.

Of those 8 in existence, only 3 are in the United States. We're told the other 2 cars in the U.S. belong to Drake and DJ Khaled.

When the car was released, the sticker price was $1.35 million -- and a Maybach spokesperson says the target buyer is "a superrich individual who wants something that is extremely extraordinary and enjoys being driven in a car with acres of sky above them."

... which is likely why Floyd wants one so badly!

Okeke is asking for $2.6 million ... or best offer.

The issue, we're told, is there's a bidding war going down behind-the-scenes between Floyd and another major celebrity -- a high-profile rap star.

We're told the bidding is already over $2 million ... and it's still active.

Floyd has made close to a billion dollars in fight money and he LOVES cars ... so you'd think he'd just pony up whatever it takes to close the deal.

But, we're told Floyd is waiting to see where the rapper draws the line ... so he can come in slightly above and not pay a cent more than he needs to.

Long story short ... seems like Floyd is ultimately going to get the car and the rapper is going to have to see if Drake or DJ Khaled are willing to make a deal.