EXCLUSIVE

5:08 PM PT -- Jerry's attorney, Orin Snyder, tells TMZ, "Jerry has been working in good faith to get to the bottom of this matter. He has asked Fica Frio for evidence to substantiate the allegations. Fica Frio ignored Jerry and instead filed this frivolous lawsuit."

He continued, "Jerry consigned the car to Gooding and Company, an auction house, which is responsible for the sale. Nevertheless, Jerry is willing to do what's right and fair, and we are confident the court will support the need for an outside evaluator to examine the provenance of the car."

Jerry Seinfeld has a hit show involving cars, and now he has a lawsuit involving one.

According to the lawsuit, obtained by TMZ, Jerry auctioned off a 1958 Porsche 356 A 1500 GS/GT Carrera Speedster and the winning bid was a whopping $1.54 million.

The buyer, FICA FRIO Ltd., says the authentication of the vehicle was bogus. What's more ... the buyer is saying Jerry intentionally misrepresented the authenticity of the whip. The suit says in the history file of the Porsche, the person who sold it to Jerry said, "Unfortunately we do not have a lot of information on the 1958 Porsche 356 A 1500 GT Carrera Speedster. We purchased the car from a broker who would not take me to the cars (sic) original location to meet the family that owned it originally."

The buyer took the car to one of the world's foremost historic Porsche dealers who expressed concern about the authenticity, and an investigation revealed it wasn't the real deal. On June 21, 2018, the suit claims Jerry called a rep for the buyer and left a voicemail that said he wanted to "offer my apology for this nuisance and assure you that you will be completely indemnified in full and not have to keep the car and get all your money back."

Porsche built only 151 Carrera Speedsters between 1955 and 1959, and fewer than 90 had the GS/GT trim the buyer thought he was getting.

The buyer says he didn't get his money, and is now suing to rescind the sale and get his money back. He's also suing for punitive damages.

We reached out to Seinfeld ... so far, no word back.