[mpg_numbers_guy]

Given the same mods being done, in most cases the Metro will beat the Echo, and the Echo will beat the Corolla/Prism. However with hypermiling and a few mods you could probably expect 40s in a Corolla/Prism, if it was a manual, 50s if you went a bit more extreme. An auto would probably get a bit lower.

How soon do you need to get a car? It took me 4 months of searching to find an Insight that was in decent shape, not too expensive, and not a day's drive away.

For mpg monster, manual Civic hybrids and Insights are also good candidates since the battery can be disabled in a pinch. Honda Fits are also good options, but around here at least they seem to be priced slightly higher.