If you want to buy a car in Bitlife will need to vist a car dealership under the go shopping tab. But before you can do this, you will first need at least 20k in the bank, as this is around how much the cheapest car costs.
That said, we recommend getting a decent job and get some money before purchasing a car. Then once you get the money, all you will need to do next is visit an auto dealership under the go shopping tab.
In total, there are three auto dealerships, and each will carry various cars you can purchase. Now to buy one, all you need to do is click one of the listed cars and then pay for it with either cash or a car loan.
Cash will simply deduct from the current funds in your bank, but a car loan will take out a loan from the bank to purchase it. You pick whatever one you want to pay for the car, but if you choose car loan, make sure you can pay it off.
After you buy a car, you will also be able to interact with it under your asset tab, from repairing, scraping to gifting it to someone like you can with a house.
You will also be able to sell your car under it's tab in assets, to do this simply hit the sell option after you click on it in the assets tab.
For more on Bitlife, check out How to Become a Mechanic in Bitlife and How to complete the Motorhead Challenge in Bitlife