I've noticed when driving across road markings on the highway in my 09 4.2 the steering wheel vibrates / twitches giving me an unstable feeling.

It's not a major problem as I simply just keep the steering wheel firm but it does not feel as it should be like this. My tire pressure is the recommended on the car. Seems like lower control arms are usually changed when knocking appears which I don't experience.

I've been searching the forum and not sure if it is the lower control arms or bushings that needs to be services. Anyone has any input or experience? 2009 L322 4.2 Supercharged

Anyone has any advice on what could be needed to be replaced or the reason for the car being too sensitive when driving on road markings on the highway? 2009 L322 4.2 Supercharged

Any garage should be able to get the car on a ramp and check for play in the bushings and any other components. From just the description it's impossible to diagnose correctly as it could be many things including;
Worn steeing rack or tie rod ends ( inner and outer)
Worn shock absorbers
Tyre out of round or wheel imbalance
Worn bushes and suspension joints
What tyres does it have ? 2012 TDV8 Vogue (L322)