Recent reports of large trucks blocking Tesla Superchargers has some comparing the practice to "rolling coal," when owners of diesel vehicles modify their engines to blow smoke.

One Tesla owner said a group of truck owners harassed them in the parking lot of a Sheetz convenience store in North Carolina.

CEO Elon Musk recently said the company was expanding the charger network.

Tesla drivers are reporting a spate of "ICE-ing" (an acronym for internal combustion engine) by large trucks at Superchargers across the US.

A Reddit user named Leicina said that in one instance a group of trucks blocked all the charging spots while chanting "'F' Tesla" before being asked to leave by an employee of a Sheetz convenience store in Hickory, North Carolina, about 40 miles northwest of Charlotte.

Like most Supercharger stations, the one where the incident occurred isn't on land owned by Tesla but leased from third parties, giving the company little control over how the charging spots are used from day to day.

"It was really uncomfortable," the Tesla owner said, adding that the Sheetz employees were "really understanding and sent someone out immediately."

A Sheetz representative said the company was aware of the incident and apologized for any inconvenience.

"Sheetz is proud to offer a wide variety of fueling options, including one of the largest networks of Tesla Superchargers," Nick Ruffner, the chain's public-relations manager, said in an email. "Parking spots with Tesla Superchargers are reserved exclusively for those charging their vehicles. These spots are regularly monitored by our store managers and employees — who routinely ask other motorists to move their vehicles."

Watch: What would happen if Elon Musk left Tesla?

Another Tesla owner in Bristol, Tennessee, said they spotted a Dodge Ram truck blocking a charging spot, with the charging cable attached to the bed mockingly.

Laws about parking in reserved spots vary by state. In Arizona, for instance, it's illegal to park in "any parking space specially designated for parking and fueling motor vehicles fueled exclusively by electricity unless the motor vehicle is powered by electricity and has been issued an alternative fuel vehicle special plate."

The incidents aren't new — Tesla owners have complained about them for years online. (Some are most likely accidental, but many, like the one in Hickory, are clearly meant to provoke.) Some have shamed their gas-guzzling peers when they park in electric-vehicle charging spots.

A Tesla representative did not respond to a request for comment.

Many people have compared the practice to "rolling coal," when owners of diesel vehicles modify their engines to dump excess fuel into the cylinders. It results in more horsepower and torque, but also black plumes of smoke when not all the fuel can be burned.

In videos posted online, drivers have bragged about blowing clouds on protesters or an unlucky Prius on the highway.

The practice has been illegal at the federal level for years, and New Jersey enacted a similar law in 2015.

Tesla CEO Elon Musk this week said the company was "dramatically increasing Tesla Superchargers within cities & working with landlords to add home charging to apartment buildings."