US car makers are forever getting fussed about offshore competition -- remember the Saturn, which was going to out-Japanese the Japanese? Still going, but it's just another American brand going nowhere.
So what's the big problem?
Design by committee and badge engineering.
Look at the Buick Rendezvous if you dare or the Pontiac Aztek (no link, it's too ugly -- well, ok here it is, but promise not to look without a throw-up bag).
Both of these vehicles are misbegotten combinations of mismatched curves and surfaces. If you look at them a small piece at a time, the pieces aren't too ugly on their own. Put them together and you have something which reminds me of the animal-drawing party game I played as a kid. You draw a section of the animal, starting from one end, then fold the page so only the ends of the lines are visible, then pass it to the next person. The result? A weird animal with the rear end of a horse, the midsection of an alligator and the front of a chicken. A Pontiac. Choose the animal parts in the opposite order. A Buick.
My guess is that companies like GM have a different design team for different parts of the car -- probably with different management processes to get design approval. Hence, no design integrity.
How can this kind of thing happen?
At least part of the problem is badge engineering -- respinning a basic design to fit marginally different niches by making it look different. The British car industry was big on this in the 1970s, and look where they are now. If a car is designed as a basic platform, with different corporate looks pasted on, it is bound to look as if it's designed by a committee -- unless a chief designer with the clout to maintain integrity is in charge.
Why is this done? For one thing, the focus is wrong -- if you have two divisions selling similar products, your mindset is how to differentiate them from each other, not from the competition.
But there's another thing.
From the look of many American cars, I would say that designers are specialized into small niches, like tail lights and door handles, and no designer is in overall control. (The project head is probably an accountant.)
This is probably cheaper because you don't have to pay some star designer to get the product right.
But making a product which no one would be seen dead in is a false economy. The market for hearses isn't that big.