What about the estimated 12 percent of Americans aged 15 years and above who don't drive, period? What about all the adults who live in the 8 percent of households that don't have a vehicle? What about half the residents of Manhattan, who took transit planners' decades-old dream to heart and "got out of their cars"? What about those who are too poor to drive? The answer: All of these people are subsidizing whoever turns in an SUV or crappy old $800 K-Car like the one I used to drive. Not only that, but what do you think happens to the $800 car market when the guvmint is handing out $4,500 checks to have the things destroyed? I'll go ahead and state the obvious: It shrinks, making it more expensive for the truly poor people, the ones who want to make that daring leap from the bus system to an awful old bucket of rust.
So no, not "everyone" was helped by cash-for-clunkers. Ah, but what about how it's better for the environment, and therefore "everyone"? Tell it to those smokestack apologists at, uh, The New York Times, The New Republic, and The Guardian.
... Cash-for-clunkers is indeed very "popular." So is the home mortgage interest deduction, the prescription drug benefit, and any number of federal programs that siphon from the diffuse pool of tax revenue+debt and blast out concentrated benefits to the broad middle class. The standard for judging these things shouldn't be popularity–Richard Nixon's wage-and-price control spasm of 1971, to name one of many historical measures now widely and rightly considered asinine, was hugely popular at the time–but whether they make sense in both the short and long term.