US entrepreneur Elon Musk will attempt to fly the world's most powerful rocket later from the Kennedy Space Center.
His Falcon Heavy vehicle is designed to have more than twice the lifting capacity of any existing launcher.
Because of the historic high failure rate of maiden flights, the rocket will only carry a dummy payload, however, the BBC reports Tuesday.
Mr Musk has decided this should be his old cherry-red Tesla sports car. A mannequin wearing a space suit will be strapped to the driving seat.
The entrepreneur says David Bowie's classic hit Space Oddity will be looping on the radio in the roadster as it is hurled into an elliptical orbit that stretches out to Mars' orbit around the Sun.
"[The car will] get about 400 million km away from Earth, and it'll be doing 11km/s," he told reporters in a briefing on Monday. "We estimate it will be in that orbit for several hundred million years, maybe in excess of a billion years."
Three cameras attached to the car would provide "epic views", Mr Musk added.
Thousands of spectators are expected to descend on Florida's Space Coast to witness the ascent, which could occur as early as 13:30 EST on Tuesday (18:30 GMT).
Mr Musk's rocket company, SpaceX, has given itself three hours to get the vehicle up on Tuesday. If technical glitches lead to a postponement, a second attempt will be made on Wednesday.
The 27 Merlin engines at the base of the rocket should be capable of generating almost 23,000 kilonewtons of thrust - slightly more than double that of the world's current most powerful rocket, the Delta IV Heavy, which is operated by US competitor United Launch Alliance.
The 70m-tall Falcon Heavy is designed to put up to a maximum of 64 tonnes in low-Earth orbit. That is like putting five London double-decker buses in space.