Tests of the futuristic hyperloop transport system have managed to propel one of its pods at 355km/h (220mph).
The tests establish a new record for the technology only days after a separate prototype hit 324km/h.
Hyperloop puts pods in an airless tunnel and seeks to accelerate them to very high speeds to cut travel times for freight and passengers.
Backers of the hyperloop idea claim that eventually the pods will travel at speeds of about 1,000 km/h.
The idea for the version of the hyperloop transportation system currently being developed was floated in 2013 by Tesla boss Elon Musk. This week saw the first tests of prototype carriages or pods on a one mile long test track near Los Angeles. A pod made by a German student team came top in this competition.
In an Instagram post, Mr Musk said that once the prototype competition was finished, the hyperloop team let a "pusher pod" travel by itself on the tunnel test track.
The pusher pod was used to get some of the prototypes moving down the track during the tests.
Running by itself, the pusher pod set the new record before things started burning, wrote Mr Musk. He described the spectacle of the pod racing down the track as "...kind of like racing with a tugboat".
Improvements to the test track might mean the pods hit 500 km/h next month, he said.
The series of tests this week suggest the technology is close to the top speed at which existing terrestrial transport technology can travel.
Earlier this month, China started letting its high-speed "Fuxing" trains travel at speeds of about 350 km/h (217mph).
It is also looking into ways to upgrade high-speed tracks to let them go faster - perhaps at speeds approaching 400km/h.