The XJ40 series cars had a number of issues in common, which are not shocking if you've done your research before buying and therefore you are not surprised. Just part of the Cat's personality.
I bought my car used, and it still had the original rear differential (known to fail prematurely in many XJ40s), which was running noisy. But for the $1,200 to replace it, the prior owner had reduced the selling price by $2,000 because he didn't want to deal with it. My gain.
The 88 electronics are quirky, but I learned to live with the ever-present "Bulb Failure" light that flashes when it pleases, even when all's well.
The 88 exterior door handles are known to break -- the driver's side and both passenger door handles broke on mine.
Water leakage into the trunk is another common issue. I just made sure that no debris got trapped in the drain-pipe near the gas cap and that solved it for me.
The XJ40 horror stories come from folks who've never owned one. The issues with my 1988 were very mild compared to the typical problems of other cars of other makes. If you take care of the Cat, and educate yourself of what your model-year tends to need, you'll never be unhappy with this fabulous-driving, beautiful car.
This has been a VERY economical car to maintain and operate -- 28 mpg, dead-on reliable and only routine and preventive maintenance needed. It never let me down. I have no doubt this car will be on the road in 10 more years, without any mechanical heroics needed.
It's a fantastic open-highway car, and just lopes easily along at 80+ at 2,300 rpm.
The engines and transmissions in the XJ40s are practically bulletproof, and my was no different. Engine and transmission are smooth as glass, even at 198K -- with plenty of power when I've needed it, awesome shifting and gear ratios to get the most out of the 3.6 engine.
I only sold my 1988 XJ40 to move into a 1995 X300 series XJ6 (which has a different set of personality traits!). One main difference between them is that the XJ40 handles more like a big limo, whereas the X300 handles like a sports car, even though these cars have the same wheelbase, weight and general dimensions.
Once you own a Jaguar of any model or vintage, it's hard to leave the jungle! I love these XJ6 6-cylinder versions.