The debate takes a whole new direction when you consider the fact that LOWer-MPG vehicles are WAY down in market value...and HIGHer-MPG vehicles are getting premium dollars. You lose your shorts in that transaction, especially at a dealer!
When deciding whether or not to "trade-in", you have to factor in how much $$$ you lost, then measure the fuel savings against that. It may take you YEARS for your fuel savings to simply off-set the loss you took buying a fuel efficient car!
I'll proudly keep those $thousand$ in my pocket, stick with my PSD, and ride this out. In the end, the diesel fuel price will end up back below gasoline, where it's always been in the past.