I have an XJL 3ltr diesel with 96k. I feel the drive is pretty firm and not a smooth ride like a Merc. You can feel every bump, pot hole etc on the road. I’m sure this isn’t normal? Occasionally there is a squeak from the rear when going over bumps. Can anyone advise me if the air suspension is faulty? I was told that air suspension is only half on this vehicle at the rear?
should this car drive like a Merc smooth over bumps?

 

Don’t the front shocks have insulators like the S-Type etc?

these pads are mounted atop the spring to acts as a buffer but deteriorate over time causing a rougher ride and eventually clanking.

I just got my XJL last month and whilst much smoother than my 170k S-Type, I do notice a less than optimum ride over some surfaces

 

Cars with 20" wheels have a harder ride than 19" wheels.

This shows a 20".

 

We have a 2014 S550 with air suspension at all four corners and a 2019 XJL with air suspension just in the rear and 20" rims. I find the overall ride smoothness between both to be very comparable. It is possible you have it on sport suspension setting? Or maybe something is wrong and it's stuck on that setting.

 

I have heard that the 20" rims can make it a bit harsh, I have 19" wheels on mine ( 2015 portfolio ) and also specified them on my last one, a 2011 luxury which I had from new, I chose these wheels as back in 2010 when I was researching the car it was suggested that they ran better on 19's , I have found that the ride is absolutely fine.
However I also have a 2015 model Mercedes S500 with air all round and magic body control and that also is on 19" rims and I would say it is smoother but not by a huge amount