Have you kept your maintenance up?

Worst case would be if your ignition system was not in good shape for a while, this multi cylinder misfire could damage or ruin your catalytic converter.

I recently purchased a used XC70 with 80K miles.

As a precaution, I had my dealer change the spark plugs - they were marked Ford - evidence that they were original and had not been changed on schedule.

Since the car had maintenance records from a private Volvo indie, I suspect that the plugs had been inspected and looked ok and were left in the car - setting me up for some sort of failure before the second plug change was due.

Another gotcha is the serpentine belt - modern EPDM belts do not show their age by cracking - they do wear out like tires and slip later in life. If you do not change them on schedule, they should be read with a gauge by a tech.