Final answer:
Marvin should buy the car that costs $4,000.
Step-by-step explanation:
In order to determine which car Marvin should buy, we need to compare the prices of the two cars. One car costs $4,000 while the other car costs $4,600. By comparing the prices, we can see that the car that costs $4,000 is cheaper than the car that costs $4,600. Therefore, Marvin should buy the car that costs $4,000.