Yes, preparation will improve your score a certain amount maybe within 200 points of what you would naturally score with your base high school education.
I disagree to some extent, the SAT tests what you know, intelligence isn't about knowing its
about your ability to learn. That being said, sure if everyone was exposed to the exact same education and experiences from day one, then sure, the SAT would test how much you were able to absorb. The reality of it is though all schools are not equal, not all schools teach exact same stuff, & not all schools focus on students acing the SAT test.
Back when I took the SAT, 1600 was the max, and was broken into effectively 3 sections, one that was basically analogies, one that tested basic reading comprehension and graph analyzing skills, one that tested basic math skills. If you went to a school that exposed you to and practiced these skills, then you did well, but many poor schools will almost pass kids through without teaching them these basic skills. So, although they may have the potential to learn, they were not given the same opportunity over 13 year period (counting kindergarten), and thus are grossly inept for the SAT test.
Rather I would argue that the SAT test, tests if you have learned the right things to have the potential to succeed in a traditional university.
