It really depends on the person reading the review about used Japanese cars whether he should believe what is said about them. Reviews come in two major categories: either the review about Japanese used cars (and perhaps the preferred Japanese used car exporter of the reviewer) was made by someone knowledgeable about what to look for in a Japanese used car for sale, or the review is simply a comment from someone who does not know much about Japanese used cars. So, like opinions expressed by people in any industry, you should always take the content of reviews with a grain of salt (meaning, be cautious and skeptical until the review has been proven correct.)
Some people may create reviews about the inner workings of engines of the Japanese used cars, with emphasis on cars made by a particular manufacturer. For example, if you know quite a lot about the engines of Toyota models from years past to consider yourself an authority on the subject, then you might be able to create a legitimate and credible review about what people should look for in engines of Toyota-branded used Japanese cars. You could then expand your scope to comparing how engines from one car manufacturer rate against the performance of engines from other car manufacturers. Other reviewers might choose to focus their opinions about the external design of used Japanese cars instead. Using the same manufacturer as our example, perhaps you could make a comparative analysis of why the Toyota model for one year has a much better design than the Toyota models for succeeding years. You could say this Toyota model has a much more streamlined design that reduces drag and fosters fuel efficiency while boosting speed, while others that succeeded it are actually fuel guzzlers due to their inefficient design. In the same manner as an engine reviewer, you could then expand your range of topics to comparing designs from one manufacturer to those made by another manufacturer. These are just some ways reviews could be written though actually the potential for finding great topics to write about are practically unlimited.
Who takes reviews seriously? Why, people who don’t know much about buying Japanese used cars, of course, because they need someone who can guide them through the maze of technical information that will meet them once they start comparing used Japanese cars to choose from. And, there might also be actual experts on Japanese used cars, such as your friendly Japanese used car exporter, who might be interested in what you have to say. Of course, if you say something that departs from conventional knowledge, you will have to be able to defend yourself with facts and examples that would support those facts. Anything said in print is actually quite damning to the author if he is proven to have used incorrect facts deliberately.
So whether you are someone who just reads reviews about some Japanese used car for sale on the Internet, or are actually someone who writes reviews, the rule of thumb to be followed is truth above all else.