I gotta step in and give some credit where it is due. I also own an '06 Fusion in addition to my 'Stang and I think it is an extremely well made car. I compared it to other cars at the same price point (Accord, Camry, etc.) and I think it is a very competitive car. The import sedans I mentioned may have it beat in some respects but they certainly don't beat it hands down. I actually think the Fusion has a quieter and more refined ride quality than either one of them. Either way you look at it, the Fusion is eons ahead of Ford's more recent efforts at a mass-market sedan (Taurus, Contour, etc.), and is definitely the best effort made by any domestic car maker.
If I have any gripe at all it would be about the fuel mileage. I agree with the previous poster, mine doesn't get near what I think it should. I can get 29-30 on the highway but I am lucky to get 20 in the city and mixed-driving. Driving the same roads in the same manner back and forth to work everyday gets me about 20.5. Here's what makes me a little upset - on the same roads I get about 20.5 out of my Mustang to