CARS is the section where you can’t raise the score significantly in a short timeframe (particular for science kids). Often med school admission tends to more leninant on CARS than other sections. How was your son prep’d for MCAT (class, tutor…)? If he scored higher in other sections, it can offset a lower CARS. I know someone with a 514 (CARS 124) got accepted this cycle by in-state schools (NY) and a private (with some scholarship money) with a 3.9x GPA.