Suspension parts simply don’t last. I’ve owned this car since it was practically new and noticed the ride start to deteriorate after about 40,000 miles. Shocks, bushings, ball joints, etc., get worn and loose and need replacing so often it’s ridiculous. The rear suspension makes an annoying rubbing noise when the temperature is below 10 Celsius, the result of a deeply buried subframe mount which needs replacing. However, its so expensive to replace, I can't justify it with my wife... I’m just going to have to grin and bear the noise on cold days.
The dealer tries to tell me I’m “hot rodding it” because the brake discs last only 30,000 miles. Nope. They’re just too small for the weight of the car. Also, the brake booster unit failed… a hugely expensive part, which I saved money on by replacing with a used unit.
I also have had problems with the power steering pump, the emissions control air pump, and the fuel pump, which makes a loud whine at certain times. To add insult to injury, these parts are priced about double a “fair price”.
Some of the replacement parts from Jaguar have also been very poor. A distributor cap with cracks in it. Shocks that leaked nearly immediately after installation…
The interior is not much better for longevity. The plastic in the dash area will randomly make a loud cracking noise… like a rock hitting the windshield. Hit a big bump, and you can actually see the dash vibrate and move. The door panels are only held on with three screws that fit into tin snaps and some supplemental rubber plugs. Of course these wear out, and then the door panels rattle. The thinnest pieces of the wood veneer only lasted about three years before cracking and literally falling apart.
The most ridiculous design fault is the door latch mechanism. It has plastic in critical areas that wears out after about the eighth year of regular use. Then the door won’t shut… or you’ll think it’s closed and locked, only to find that it will swing open going around a turn, or blow open at high speeds. I can barely believe Jaguar would have made something so dangerous… I’m sure there have been lawsuits around the issue.
The oxygen sensors were a big problem too. Every few thousand miles the check engine light would tell me that one of them had failed…. A recall fixed the problem with a better ground to the sensors.
The J-gate shifter is now wobbly, and the automatic lockout - to keep the car from starting in gear - has failed once.
I have read the other reviews by XJ12 owners. It seems their assessments and experiences with the car are roughly in-line with mine: The reliability, durability, quality - whatever you choose to call it - is only average to poor. No question about it. BUT, the performance and character of the car is wonderful. An odd combination.
Its funny to me, the V12 engine - which is what everybody assumes will be the unreliable part of the car - has been nearly flawless. It barely uses any oil, pulls like a train, never misses a beat. It has great sound, eats gas, and makes huge heat. But, aside from the usual maintenance, it has needed only a new crank sensor for the fuel injection metering, and a replacement radiator. The engine/transmission combination simply MAKES this car. Otherwise, its not worth the effort.