Definition of "clunker"

The only rig nobody'd recognize is that clunker that Vic drove here in, and he won't take it.

2004, Teralee E. M. Bird, What the Herald Angel Sang (Seraphim Trilogy Book One)

So don't think for a moment that your old but tired vehicle matters only to you. Your clunker is cash money to professional thieves.

2008 July 9, Jacqueline Mitchell, “America's Most Stolen Vehicles”, in Forbes magazine

It seemed silly for the crowd to applaud or groan over what you had already felt in your fingers or even in your arms as you braced to shoot or for that matter in your eyes: when he was hot he could see the separate threads wound into the strings looping the hoop. Yet at the start of the game when you came out for warm-up and could see all the town clunkers sitting in the back of the bleachers elbowing each other and the cheerleaders wisecracking with the racier male teachers, the crowd then seemed right inside you, your liver and lungs and stomach.

1960, John Updike, 'Rabbit, Run', page 34

I bought an old clunker of a typewriter.

1974 October 3, Erma Bombeck, “Who's Been Playing At Erma's Typewriter?”, in Ocala Star-Banner, retrieved 2 September 2009, page 12A

All of the stories have a subtle undercurrent of brutality, and the writing is consistently sharp, direct and darkly funny, and there’s not a clunker in the bunch.

2006, Elizabeth Crane, "Books: Best book by a Chicago author" (Review of Trouble by Patrick Somerville), Time Out Chicago, 28 Dec. (retrieved 2 Sep. 2009)