So here's a question:
As Jews we are responsible for tikkun olam, healing the world. Many commandments concern our obligation to the planet and the environment; even kashrut is in no small measure a discussion of how to live in harmony with the planet.
As Jews we are told to avoid envy; coveting others' property is one of the Top Ten commandments. Judaism doesn't go for "thought crimes" as much as some religions, but many sins do derive in one way or another from this basic point of "I want what you have": theft, adultry, kidnapping, rape, even idolatry.
So what's the proper response when I find myself coveting my neighbor's Prius?
I guess the first question is how pure my intentions are; is my desire in this case just for the newest, fanciest car, or does it stem from a genuine environmental concern? I don't know how much of a theological difference this makes, but practically it seems major. Wanting the car car is obviously greed for a material item, while wanting to live more fuel-efficiently is a legitimate expression of my desire for tikkun olam. In that case, it's not even the car I truly desire but what it represents.
The next question is do I want my neighbor's car specifically - with the souped-up stereo system and funky paint job - or would any car satisfy? Again, this may be more a practical difference than a theological one. In this age of mass-production, coveting your neighbor's goods is not the same issue it used to be. In terms of livestock, the differences between specimins can be great, and I cannot easily get the "state of the art" model just by visiting the local horse vendor. By contrast, one iPod is much like another. The computer my roommate gets may be better than my own, but I can easily get a similar model if I am willing to put the time and money into it. Admiring, or desiring, another's posessions becomes more a recognition of their taste and judgement in the matter, and specific goods are less important than the sensibilities that underlie the selections.
There is a word that applies in this situation: tingo, from the Pascuense language of Easter Island, meaning: "to take all the objects one desires from the house of a friend, one at a time, by borrowing them." I haven't read the whole book on the subject, but as I understand the concept, tingo is a compliment; a statement of your friend's excellent taste rather than of greed. Asking tingo reflects well on you, first because it demonstrates your stylish nature, and secondly because the giving of the object shows your wealth and generosity.
So in this age of heightened eco-consciousness, coveting my neighbor's Prius may be a modern expression of tingo rather than the greed that proceeds theft and ill-will. I am admiring your personal committment to tikkun olam and the ways you incorporate it into your life. The world may be ready for the return of tingo, with the slight change that instead of actually taking my friend's posessions, they become guides in my own quest for sustainable living.
I don't recommend or endorse giving your car away to an interested friend, though; the concept of tingo originated in a pre-industrial culture where the most expensive posessions could be replaced by a few days of crafting, after all.