The facts vary tremendously from source to source. I'm sure that ethanol could be made much more cheaply in the U.S. than it is now, with economies of scale and an efficient infrastructure.

Last night on the ABC national news, there was a piece on ethanol in Brazil that painted an entirely positive picture. The great majority of new vehicles are flex-fuel, and run on E85 at less than half the cost of gasoline. This has enabled Brazil to become entirely energy self-sufficient. There was no mention of how much rainforest was lost to sugar cane fields (I don't know how much, but I would bet real money that there's a substantial environmental impact).

The handful of people who are running their cars entirely on waste products -- old deep frying oil, for instance -- have got the problem knocked. Seems to me, though, that whenever fuel has to be produced intentionally for the purpose of powering cars and machinery, there's always an environmental downside, no matter what the fuel is. So far I haven't seen anything that I'm convinced beats gasoline overall -- not by much, anyway. Same for hybrid and electric cars -- a 1980 Honda Civic uses less fuel.

From an environmentally green standpoint, two things need to happen: 1) vehicles must get far greater fuel efficiency than they do now, and 2) we should drive less -- much less. Both require serious cultural changes, the second more so than the first.

But to get back somewhere near the original topic of this thread... I don't think driving old Volvos is necessarily environmentally hostile. Well maintained and properly tuned, they easily exceeed the CAFE standards for fuel economy. There's no problem using unleaded gas. We're pretty much all running on some ethanol blend now, and in many areas have been for years with very little ill effect (mostly just requires replacing the original fuel lines with something more modern). They're not as clean as the latest cars, but far from being "gross polluters" either -- I was always able to pass California smog with lots of margin to spare until we moved away in 1998 (and no longer have smog checks for those cars), and that's without any special retuning, additives, or any other tricks.

There is a lot of merit in the car already existing, too. A bunch of energy is consumed producing a new car, and a lot of pollution -- more than an old Volvo will emit in decades.