Green’s Dictionary of Slang

1. (orig. US) to accelerate, to drive extremely fast.

1954		Mansell & Hall ‘Hot Rod Terms’ in AS XXIX:2 96: Floor it! v.phr. ‘Step on it.’.
1966		H.S. Thompson Hell’s Angels (1967) 129: I swung a left at Merced and floored it for a long roller-coaster-run through the foothills.
1978		R. Caron Go-Boy! 65: I floored the gas and we tore out of there.
1981		H. Gould Fort Apache, The Bronx 351: Murphy floored the gas pedal.
1997		N. Barlay Curvy Lovebox 94: I’m floorin’ it down the Harrow Road.
2015		I. Welsh Decent Ride 330: Shut the fuck up for a minute pal, ay, ah tells um, n ah fuckin well floors it.
2018		C. Hammer Scrublands [ebook] He considers flooring it, red-lining the rental, sweeping past his former colleagues.

2. (US) in fig. use of sense 1, to hurry, to get a move on.

1978

Eble Campus Sl. Apr. 2: floor it – get moving or speed up. Well you’d better floor it if you are going to go this weekend.