Hello,
i am new to the forum. I have a 2009 S60 for my daughter. Vehicle has 134,000 miles. Recently when accelerating the vehicle vibrates. There are no check engine lights indicating a problem. I would like to take care of this issue before it becomes a bigger issue but do not know where to begin. Anyone have any idea what is causing this.

 

a few things come to mind 1) motor mounts/torque rods 2) axle issues (check for torn/leaking CV boots) 3) wheel bearings 4) engine misfires.

I'd probably start by inspecting the axles and motor mounts, then do some simple tests for the motor mounts (like "torque braking" with the hood open to see if the engine moves around - particularly at the nose). Wheel bearings typically moan and change sound turning left or right so I'd rule that out. I'd also think a misfire issue would result in a CEL so that leaves me thinking axles or motor mounts

 

If it vibrates/shakes the steering wheel when accelerating (35-65 mph) and does not at a steady speed or decelerating -

A common cause of that is a worn cv joint in an axle. Usually the right axle wears out first. There are many choices of axles available ranging in price from $79 to $700. Some of the cheap (poor quality) axles are worse than the axle you will take out. Best bet is the OEM manufacturer or the factory axle.