driveway effect
n. A special quality exhibited by a radio program that causes listeners to stay in their cars after they have arrived home so they can hear the end of the program.
Examples
2013
Cohost Tony Kahn says the program aims for the "driveway effect," a story so compelling that a listener arriving home stays in the parked car after a commuting trip to hear the end of it on the car radio and then repeats it to someone at home.
—Donald R. Shanor, News From Abroad, Columbia University Press, August 20, 2013
2001
Affairs of the Heart is a case in point.

Commissioned by the Manitoba Chamber Orchestra and the CBC back in 1997, it caused the CBC Radio switchboard to light up with calls from listeners when it was first performed.

"There was what they call the 'driveway effect,' Mozetich says. People stayed in their cars in their driveways long after they'd arrived home in order not to miss the ending.
—Hugh Fraser, “Hooked on classics,” Hamilton Spectator, February 27, 2001
2000 (earliest)
Democracy Now! is one of only two nationally syndicated Pacifica programs. The other is the Pacifica Network News, which itself is seeking a new host. (Veteran anchor Verna Avery Brown was let go in a dispute last year.) The job announcement from Steve Yasko, Pacifica's national program director (and Goodman's supervisor) who formerly worked in the marketing division at National Public Radio, reads in part: "If you cause driveway effect, we'll make you a star!" Credentials for the position include: "Natural curiosity a must, public radio experience a plus, but commercial radio personalities are encouraged to apply."
—Laura Flanders, “Democracy Now! or Never,” In These Times, November 27, 2000
Notes
NPR listeners often have "driveway moments": they are so engrossed in a story or discussion that they can't get out of the car until there's a break. When someone else mentions that moment you feel you've met a kindred spirit.
—Susan J. Douglas, “A search for community,” Newsday, December 06, 1999
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