If you have hub caps, you have steel wheels.

The base model 850s came with steel wheels, alloy wheels were an option.

Besides looks, there are advantages and disadvantages to alloy wheels.

Alloy wheels reduce the unsprung weight of a vehicle, which is better for handling and ride. But the differences, in non-racing situations with a production car, are going to be inperceptable.

Alloy wheels are more vunerable to damage and corrosion than steel wheels. And, because they are appreciably more expensive than steel wheels, the cost of ownership is much higher. If you you want to spruce-up your car, with respect to its wheels, with steel wheels, you buy a new set of hub caps. With alloy wheels, you have to send them out to be professionally repaired, at the cost of $100+ per wheel.

In summary, on the street, the greatest advantage of alloy wheels is in how they look. And, if that is important to you, spend the money on alloy wheels.