^^^^show data backing this up please.
Eeeeee127, that’s not official data. Do you have an official link published by UNC that states the 90% placement rate? Michigan’s 56% figure is documented on the official Michigan website. I am very skeptical of such claims. There is no such thing as a reliable list of “best premed schools”, especially if schools within it claim a 90% placement rate into medical school.
Cornell and Penn brag about 65%-75% placement rates respectively, and that is usually based on students that were allowed to complete there application through the advising and career office, which usually turns away students that lack the academic substance to make it into medical school. There are many students at those universities who apply to medical school, but they are not tracked by the advising and career office. If you include those applicants, the placement rates for those universities will drop. As a public university, Michigan must welcome all applicants, regardless of their academic credentials. The same goes for UNC, which makes its 90% claim all the more bewildering.
A 90% placement rate university-wide is unheard of, so if UNC is making such a claim, take it with a healthy pinch of salt! 
I will repeat what I said above. For students who are naturally inclined toward the sciences, especially Chemistry and Physics, Michigan is a great place to prepare for medical school…certainly as good as UNC. For students who aren’t scientifically inclined, Michigan could be hell because the faculty is intransigent and unobliging when it comes to academic rigor and grading.
In order to effectively compare the effectiveness of a university’s medical school placement, you need to have a detailed breakdown of the type of applicants, such as this:
https://careercenter.umich.edu/article/2014-medical-school-application-statistics
According to Cornell University, for the class of 2013, 71% of medical school applicants with GPAs of 3.4 or better were admitted into medical school. At Michigan, for the class of 2014, 66% of the applicants with 3.4+ GPAs were admitted into medical school. That enables us to compare, albeit crudely, the effectiveness of both universities. It is safe to say that Cornell and Michigan have similar placement rates, when comparing apples to apples.
http://www.career.cornell.edu/paths/health/medschool/charts.cfm
Hopefully the OP is about through with Med School by now 
how come at harvard the med school placement rate is 95% if you have a gpa of 3.4+ even though there’s severe grade inflation at harvard? why is umich only 66% for gpa 3.4+ even though many people at umich were definitely well qualified for harvard? it’s much harder to get a high gpa at umich than at harvard. do medical schools take account of the grade deflation at umich? it seems like they favor harvard over umich even though it’s harder to get a high gpa at umich than at harvard. @Alexandre
Eeeee127, Harvard is probably an exception. The placement rate into medical school for students with 3.4+ GPAs at most universities will be in the 70% range, as is the case with Cornell and Michigan.
do you know why harvard has such a high placement rate compared to umich? @Alexandre
It is hard to know for sure Eeeee127. I guess we can fall back on the cliche that Harvard is Harvard. Perhaps graduate schools do give Harvard students some sort of priority.
Just look at any top graduate school out there, and Harvard will typically be the second most well represented undergraduate school. For example, at JHU Medical school, according to a 2012 report, 67 medical school students completed their undergraduate studies at JHU. That is fairly typical. Most medical schools give priority to their undergraduate students. Harvard was second with a whopping 44 students. Yale was third with an impressive 32. All the other elite universities had anywhere from 5-19.