That's a common miscalculation.

Having a smaller car can easily save you $200 per month or even more depending on how much you drive. People are routinely spending an extra few $10k to buy a bigger vehicle (or spend an equal amount of money for a truck lease), and after that they say they couldn't afford to spend $200 to rent a truck for a day.

The thing is that you often don't see the cost of a large vehicle (or of any vehicle in general). While you drive, you don't pay for anything. Infrequently, you pay for a whole tank of gas, and once a month you pay for insurance, and even less frequently you pay for maintenance. And value depreciation is something you don't even see at all, it just occurs.

All of that is more or less hidden cost. When you get into your car you don't go like "Ok, this drive down to the super market will cost me X$ in fuel, Y$ in insurance, Z$ in maintenance and Q$ in depreciation".

But if you rent a car, you clearly see all the cost upfront, so it seems much more expensive.