OK, it seems clear that many - including those in the media - are confused about the different ways in which we can make our autos more efficient and less dependent on oil. For example, the link below brings up a CNET.com article explaining a wide variety of new powertrain technology. Its major flaw seems to be in that it treats each technology as some sort of separate alternative, while it's possible to "mix and match" combustion techniques, and drivetrain architectures. One example might be an HCCI engine that burns a variety of liquid or gaseous fuels and is coupled to a series or parallel hybrid drivetrain with plug-in capability. Our readers have often pointed out the same thing, such as in the Comments section on the post we did on diesel vs. hybrid. Three people commented that diesels can be mated to hybrids, and one pointed out that diesels are very tolerant of biofuels. I think the point here is that there's a lot of ways to skin this cat, and our transportation salvation is unlikely to be as simple as implementing a single energy-saving technology.