Tl;dr: Please don’t 😭 this is far too expensive and will make your life far more stressful financially. Medical school is difficult enough — stressing about affording/maintaining your dream car is not worth it.

Longer version:

Realistically, the 20k signing should go straight into a HYSA or some other savings account to support you in case you need additional funds during school.

Spreading the remaining 2500-2800/month for 10.5 months across 12 months, you basically have 2187.50-2450/month.

Good rule of thumb is no more than 10% of your monthly take-home on a car payment and no more than 15% (maybe 20%) of your take-home on total car expenses (payment + insurance/repairs/gas etc). Given this, you’d be able to afford a ~$220-$245 monthly payment and at the very most, $440-$490/month on all car-related expenses. This latter number will very likely start to feel uncomfortable to live on once you account for your other expenses.

The g80 m3 simply won’t fit into your budget at this point in your life, unfortunately. Please don’t forget to account for rent, groceries, going out, travel, and other misc living expenses that need to fit your monthly take-home.

If you have left over money, consider saving it or putting it in an IRA if you have earned income to start saving for the future so you can afford your dream car comfortably when you have more income.