If you use the cupholder a lot - like my wife, who cannot travel without a caffeen supply at hand, you could add an insert to the cup holder.

I our case, I cut off the bottom of one of those "king" size Burger King cold cups. One of the huge cups that taper at the bottom in order to fit in a regular cup holder. I cut it off above the section that tapers, and inserted it in the bottomless cup holder. Her coffee cup fits into this insert.

(In our 740, I removed the top of the armrest and added a large plastic cup attached to a small piece of plywood to serrve as a cupholder. Cost far less than Volvo's solution!)
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3 8s & 2 7s 740,000 miles total