I think the best thing the auto makers can do is to "retro-style" their cars. The '05 Mustang is a great example of this; it's the first modern-era Mustang that really looks like a Mustang!
I'd love to see the re-introduction of the late 80's (7th generation?) Corolla style. That was a sharp looking car! I'd keep certain modern touches like the 15", 5-lug wheels, but I want a Corolla that looks like an automobile, not half of an upside-down watermelon with wheels on it. The '03-present Corolla looks OK, if anything, I'd tolerate just very minor variations on that styling but nothing too radical.