Buy a small four-cylinder car. Everything else really doesn't count for much. So it would take ten years to break even on the higher price of the vehicle. And that's assuming these new technologies won't have higher maintenance costs over the life of the car itself. I'd also guess that these hybrids won't do as well in winter and won't tow as much.
Diesel engines save fuel too, and have become quite popular in Europe.
But diesels have a tough time passing our emission regulations because the diesel sold here isn't as clean as the diesel sold in Europe. And even though, in Europe, Volkswagen and Audi are building fine, high-mileage small cars that get 70 mpg, they aren't selling well enough. In short, new technology can help but there are no miracles. Toyota and Honda have such powertrains, and so have VW and Audi. But GM, Ford and Chrysler lag in this area, and that's why many of their midsize cars are sold with six-cylinder motors rather than with fours.