Considering 2010 XC60 with 74K miles

[mrbrian200]

Turbo engines get sluggish if there's much of anything not working perfect. A 3L high pressure turbo should feel reasonably zippy in a 4100lb vehicle. Probably comparable to a S60 (~3200-3600lb) with the 2.4-2.5L Turbos which is anywhere between not bad and fast enough to impress most people. I would go back to that seller and ask if you can take it to get/or run a compression test on site. If that comes back good on all cylinders see if he'll come down on the price to account for needing to get the engine/emission system looked at by a specialist. If this engine was affected by the torn PCV diaphragm issue and was run for a time without being fixed, it could be excessive back pressure/plugged catalyst. But you can probably come up with good used part without spending +$1000 if you're patient.