Cars can tell us a lot about the people who own and drive them, though in all fairness, it's not always clear what someone's car is saying. Few cars will mean the same thing to all who clap eyes on them. But some do, and in this select group are the ones that unmistakably, incontrovertibly cry douchebag.
Pardon our French, but the D-word is only the latest overused, off-color term to describe the phenomena of universal hate-ability that accompanies some people, and, as it happens, some cars. Not long ago, "*******" was one such all-purpose term. The sad historical fact is that D-bags, *******s, jackasses, et al have always been loose amongst us, walking the planet since homo became erectus. For the last hundred years or so, they've been driving on it, too, often like jerks. Hence the phrase "douchebag car": It's a concept as old as motoring itself.