A Tesla owner says he makes up to $800 a month mining cryptocurrency with his car. He says it's worth it, even though it could void his warranty.

• Siraj Raval told CNBC that his Tesla Model 3 mined bitcoin and ethereum for about 20 hours a day.
• He called his car a "computer with wheels" and said he made $400 to $800 a month.

The owner of a 2018 Tesla Model 3 told CNBC that he made up to $800 a month by using his car to mine cryptocurrency.

Siraj Raval, who described his car as a "computer with wheels," said he'd plugged an inverter into a power socket in his car and used it to power a computer running bitcoin-mining software.

He said he made $400 to $800 a month, depending on the value of bitcoin and ethereum. Even though it could void his vehicle warranty, which covers the battery for up to eight years, he believes it's worth it, he said.

"It's so simple to hack into this computer car," he said.

He said he'd also used the car's battery to run interconnected graphics-processing units that mine cryptocurrencies.

Raval said that he spent roughly 20 hours a day mining with his Tesla battery and that he paid $30 to $60 a month charging the battery.

Chris Allessi, an electric-vehicle dealer in Wisconsin, told CNBC that using a Tesla to mine cryptocurrencies wasn't worth it.

Because he bought his Tesla before 2017, Allessi got access to the company's free lifetime Supercharging program, meaning he doesn't have to pay to charge his battery. He said that he used this free power to mine cryptocurrencies but that he gave up because it wasn't profitable enough.

"Did it work? Yes. Did it mine anything worthwhile to be able to be profitable in any way, shape, or form? No," Allessi told CNBC of his experience mining monero.

And despite bitcoin's soaring value, Allessi estimated that the growing difficulty of mining meant that if he were to mine it now he'd get about $1 or $2 worth of the cryptocurrency in 60 hours.

"Why would you want to put that kind of wear and tear on a $40,000 to $100,000 car?" he added.

"The difficulty is so high," he said, adding, "I could make more money working at McDonald's."

Thomas Sohmers, a Tesla hacker and cryptocurrency miner, told CNBC he doubted Raval's claim, saying he didn't think it would be possible to make so much profit by using his car for mining.

But Raval said he didn't plan to stop mining cryptocurrency using his Tesla. He said that in the future he wanted to make his car a fully autonomous robotaxi that mines whenever it's not on the road.