My feeling is that it's difficult to make a persuasive argument for protectionism being a factor in the lack of success of the US auto industry overseas, because nobody other than Americans even tries to buy US autos. By "US autos" I mean cars designed and built by US companies for the US market, not cars from companies (such as Saab or Jaguar) where owner may be American (e.g. GM) but the company is clearly not. Honda makes cars in the US and for the US market but the approach to design and manufacture is Japanese through and through. Renault owns a chunk of Nissan but that doesn't make Nissan French; it's still very much a Japanese company.
What this means is that you'll see the odd Hummer or Grand Cherokee rumbling about in Europe or Japan, but the volumes are tiny. Why is this so? My guess is that this is because US cars (using the above definition) are built very much for the US market and make no allowances for other regions. Take a Lincoln Town Car or whatever those things that the NY limo companies use are called. It's roomy inside, yes. It's also a bulky, thirsty, car that wallows horribly and has a cabin made from cheap plastic and fake chrome. Americans no doubt have good reasons for liking this kind of car: cheap(er) fuel prices; plenty of internal space for those, ah, larger citizens; the assumption that roads will wide and straight and will not require sophisticated suspension; a cultural preference for a lower price tag rather than a pretty interior.
On the other hand, nobody outside the US chooses one of these over an Audi or a Mercedes or even a VW outside the US. The question of "value" would be irrelevant for most Europeans in this case - a couple of thousand dollars difference in price (which is what import duties in theory might cost a buyer) would not matter. Nor would it matter in Japan. Different cultures really do perceive these things differently, which may be hard for some people to accept, especially those with relatively little experience of other cultures. If you don't accept that other cultures tend to have different priorities, the tendency is to start looking for other explanations, like protectionism.
In my not-so-humble opinion, The US does many things well relative to other countries. Cars are not included in this category. The only exception to this rule is Ford, which has for decades been using international designers to tailor cars to local markets. Cars like the Mondeo and Focus are certainly competitive in Europe, but then nobody regards them as "American" cars. I visit the US frequently but I couldn't name a family sedan made by a US company. I'm sure I must have seen hundreds but all I remember seeing is trucks.
As for quality reviews, one thing to bear in mind is that many of these are based on problems reported by the customer. As you can imagine, the more expensive the car, the less likely the customer is to ignore something he perceives to be an issue. The expectations of a BMW owner are very different to those of somebody who buys a $15,000 entry level car. In absolute terms the quality of the BMW is probably significantly higher, but if the owner is dissatisfied with (say) the feel of the leather on the steering wheel he's likely to tell researchers that it's a problem when they ask, while the driver of the $15,000 car probably would not even mention it. So this might in some cases lead to the overstatement of "problems" in ALL higher-end cars, which is a market currently dominated by the Germans. (This is not to say that they don't have real problems as well, such as the well-known Mercedes electrical gremlins.)
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