Now where do I start? Bought the car March 2010 with 163,700km (just shy of 102k miles) and since then replaced the following:
March 2010: Alternator - warranty
April 2010: Complained about juddering - got free SCV kit under warranty, they refused to replace them
September 2010: Front wishbones, drop links, tie rods, tie rod ends, 4 wheel alignment - vibration persisted even with new tyres
February 2011: 6 new injectors - problem persisted, lower fuel consumption
March 2011: Disks and pads, front and rear, rear upper control arms, GM parts - problem still there
July 2011: Steering rack gave up the ghost, my own fault for not checking for splits in the boots - problem still not solved
September 2011: Loss of fuel pressure, replaced the SCV's - vibration still not gone, lower fuel consumption
December 2011: Fitted a Steinbauer tuning box in hope it would help with reinterpreting the signals from the ECU and somehow make it run different - lower fuel consumption, still vibrating
March 2012: 2 front springs, top strut mounts, drop links and ARB's -
The mechanic said the car's suspension looks and feels sound!
Known faults: Rattle when I lift off the clutch
I have learnt to live with the fact that this car behaves differently every day of the week. One day it will smoke, the next day it won't. On a Wednesday morning it will decide not to vibrate much but will 6 hours later change it's mind entirely...
When the car decides it wants to be a vibrator:
The vibration is felt through the car at speeds higher than 30mph. Hard acceleration makes it worse. Higher speeds and power demand (full throttle in Germany for example, accelerating from 90mph in 6th) make the ride quite uncomfortable. The vibration is worse if the Autobahn has a slight bend and I drive 120+ (or even slower sometimes).
When the car doesn't vibrate much:
The vibration is felt at 60mph+ although not severe. Accelerating from 90mph in 6th will cause very little vibration. Speeds higher than 130 still make the car vibrate. Can feel stronger vibrations through corners at higher speeds.
What has been happening lately is that the vibration is felt like a pulse, as if you had a switch for a lady toy...on off on off on off...It will shake for a split second, then stop while still vibrating slightly, and again shake...
The things that haven't been checked are the engine and gearbox mounts, rear drop links, shock absorbers (these look fine and do not leak oil) and driveshafts.