I think the quesiton you should be asking yourself is which is more important to you: Reliability or fuel economy? Sometimes you can get both at the same time, but the choices you're presenting -- the Highlander vs. the Escape -- don't qualify. So, which is it?

The problem with too much idealism towards fuel economy, or in choosing a statement vehicle in general, is that you can compromise some of your other good judgements and end up getting burnt. For example, Ford is improving their reliability but they're still not up to Toyota's standards. Biodiesel sounds good in principle, but will you find it wherever you drive, and will the auto manufacturer endorse a quality standard that won't ruin your engine? Good luck getting a statement from any of them that will qualify anything above B5 (5% bio to 95% diesel), and if you're found using higher levels you may be refused warranty service.

I can't speak for your vehicle choices, but I have been burnt by idealism, which is why my second vehicle choice (Honda Civic Hybrid, 2nd gen.) was a much more sober one.