Tesla CEO Elon Musk has traded barbs with Turing Award winner Yann LeCun over a video of the next-generation Roadster performing a brief hop, a demonstration that has divided the tech world. The video, posted on X, shows the electric sports car leaping off the ground using cold-gas thrusters, which Musk captioned: "Turns out the future does have flying cars." The clip quickly drew millions of views, according to the Chinese tech news outlet 快科技 (Kuaikeji), which first reported the exchange.
LeCun's physics critique
LeCun, a former chief AI scientist at Meta and a Turing Award laureate, responded with a technical takedown. He argued that the cold-gas propulsion system has an extremely low specific impulse of under 50 seconds, meaning that even if half the vehicle's mass were compressed gas, the thrust-to-weight ratio would exceed 1.0 for less than 10 seconds. "The demo is cool, but completely impractical," LeCun wrote, adding that the Roadster would need to be a lightweight shell with massive compressed gas tanks. He later clarified that the system uses compressed nitrogen (N2), not hydrogen peroxide, and is derived from SpaceX's cold-gas thruster technology.
Musk's reply was a social media moment. He quoted a line from the British comedy film Monty Python and the Holy Grail: "I fart in your general direction," complete with a fart emoji. The exchange went viral, with netizens joking about a "fart car" sparking a war of words between a Turing Award winner and the world's richest man. Some even sent LeCun images suggesting he should wear a gas mask.
Mixed reactions and practical hurdles
Google CEO Sundar Pichai took a more positive stance, commenting on Musk's post: "The FSD version will be great, congratulations!"—a nod to Tesla's full self-driving software potentially pairing with the flying Roadster.
Observers in aerospace and automotive circles note that cold-gas thrusters are suitable for short, demonstrative hops but cannot sustain flight. The high-pressure tanks are bulky and heavy, eating into passenger and luggage space. Tesla has not announced a commercialization timeline for the flying Roadster, which Musk has framed as a futuristic option for the next-generation model. Significant engineering hurdles remain before it could receive legal road approval.
