Tesla CEO Elon Musk announced in a Saturday tweet that a “SpaceX option package” for the forthcoming Tesla Roadster will “include ~10 small rocket thrusters arranged seamlessly around the car” to improve performance.
That may sound, well, ludicrous—and Tesla HQ has said that as a general policy it doesn’t confirm or deny the veracity of Musk’s tweets. But some of Musk’s most apparently ridiculous Twitter brainstorms have wound up being absolutelyreal, and Musk Sunday morning provided further technical details that suggest the rocket-car plan is, too.
SpaceX option package for new Tesla Roadster will include ~10 small rocket thrusters arranged seamlessly around car. These rocket engines dramatically improve acceleration, top speed, braking & cornering. Maybe they will even allow a Tesla to fly …
— Elon Musk (@elonmusk) June 9, 2018
These would not be flame-spitting jet engines burning rocket fuel—that would, among other problems, almost certainly not be street legal. Instead, the thrusters would be small, extremely strong vessels holding highly compressed gas. Musk said in a tweet that the enhanced Roadster would use COPVs, or Composite Overwrapped Pressure Vessels, which are used on the SpaceX Falcon 9 rocket for tasks including steering the rocket in space, rather than for main thrust.
Note, gas contained would be ultra high pressure air in a SpaceX rocket COPV bottle. The air exiting the thrusters would immediately be replenished whenever vehicle pack power draw allowed operation of the air pump, which is most of the time.
— Elon Musk (@elonmusk) June 10, 2018
Get Data Sheet, Fortune’s technology newsletter.
Musk also wrote Saturday that the “New Tesla Roadster will exceed all gas sports cars in every way.” One thoughtful Tesla watcher speculated in depth about just how profoundly the use of compressed air thrusters could change the very nature of a high-performance car. They could be used not only for acceleration, but enhanced braking using forward-facing thrusters, better road grip with upward-facing thrusters, and highly enhanced handling at speed using side thrusters. Even Musk’s comment that “maybe they will even allow a Tesla to fly . . .” isn’t necessarily an exaggeration—the thrusters might be able to provide directional assistance when a car leaves the ground, such as after cresting a hill, or even let the car hover for short periods.
Notably, the failure of one of a SpaceX COPV played a role in the Sept. 1, 2016 explosion of a Falcon 9 during fueling. In that case, a COPV tasked with injecting helium to maintain fuel tank pressure failed. Earlier this year, an oversight panel advising NASA raised questions about the use of COPVs for crewed missions. SpaceX has agreed to a safety redesign that would presumably be extended to units used in the Roadster SpaceX package.
Musk also hinted that Tesla would go “a lot further” than simply using compressed air, without providing specifics.
Using the config you describe, plus an electric pump to replenish air in COPV, when car power draw drops below max pack power output, makes sense. But we are going to go a lot further.
— Elon Musk (@elonmusk) June 9, 2018
The new Tesla Roadster—an update of Tesla’s first, ultra-premium sports car—was revealed in late 2017 at an event also announcing the Tesla Semi. The new Roadster is projected to be available in 2020, with a base price of $200,000. No details yet as to how much the SpaceX thruster enhancements might cost.
