去大学要换两辆车

If you mean "going to the university needs changing twice in transportation" then the sentence should be, 去大学要换两次车

Do you mean you need to buy a new car when you go to the university? Then 两 should be changed to 辆。 They have the same pronunciation but different meanings. 辆 is the quantifier for vehicles while 两 means two.

要記得加上量詞，所以應更正為去大學要換兩次車，另外，你也可以說轉兩次車、換兩趟車、轉兩趟車，意思都相通。