Don't forget to check the 'frunk' in a rented EV! A Hertz customer found a slab of rancid meat in his Tesla.

• Rental fleets are adding more EVs, which bring a learning curve — like realizing there's a "frunk."
• A Hertz customer found 10 pounds of rancid meat in his rented Tesla's front trunk, the WSJ reported.

Rental car fleets are adding electric vehicles — and with those new EVs come a learning curve for some drivers — like remembering there's a "frunk," or front trunk.

One driver apparently forgot their grocery order and left a package of meat in a Tesla Model 3 rental from Hertz, the Wall Street Journal reported last week. The next renter made the unlucky discovery: Costco bags and a 10-pound pack of rancid meat that he told Insider was absolutely pungent.

"Buried underneath the pile of groceries was the source of the stink," Marc Froemelt told Insider. "There was a slab of meat — at least 10 pounds — that had burst out of its vacuum seal and had started oozing juices. Some of it had caked on, and it was the most disgusting smell."

He shared a picture with Insider after his story was featured in the Journal — and it's obvious what had been once in the frunk from the congealed juices left behind in the Tesla, which Froemelt, who's from Atlanta, rented at New York's LaGuardia Airport.

Leaving a 10-pound hunk of meat in a car seems like a potentially silly thing to do until you realize: Most drivers might not remember there's a storage compartment under the hood of the car — what's actually the frunk in an EV since there's no gas-powered engine.

The frunk, a term for the space in the front of many electric cars, has entered the everyday vernacular of many EV owners by now. The feature has even drawn a sort of fanbase of its own — there's talk of the Tesla Cybertruck's apparently tiny frunk, odes to the Ford F-150 Lightning's massive frunk, and even comparisons of the best frunks across different vehicles. But those who aren't as familiar with EVs, however, might easily forget about the frunk.

That's what apparently happened to the person who rented the Tesla before Froemelt.

According to the Journal's report, on a hot day in May, Froemelt was making good time driving down the Long Island Expressway on a trip to visit his mother-in-law.

He told Insider that he noticed the strange smell, but attributed it to odors from the roadside. It was only when he parked the vehicle in the driveway that he realized the smell was coming from the car itself, and opened the Tesla's frunk to find the pile of groceries.

The large, rancid slab of meat that had somehow been left by the previous renter and apparently passed over by the rental agency when the vehicle was returned and re-rented.

Froemelt traded the car for another Tesla at another Hertz location and got the rental refunded through his credit card company when Hertz only offered a $50 credit, he told the Journal. Hertz didn't respond to Insider's request for comment; it also didn't comment to the Journal on Froemelt's discovery.

While a frunk full of rotting groceries is an unpleasant surprise, it's certainly not the strangest use case for an EV's frunk.

After Ford released its Mustang Mach-E, the company posted a list of tongue-in-cheek suggestions for how football fans could use the vehicle's front trunk to "elevate their tailgates" by using it as a cooler, filling it up with hot wings, or using it for a game of cornhole.