Jaguar kept the 5.3-liter V12 in production from 1971 through 1992, and when it was running properly — which wasn't as often as XJ-S owners wished— it couldn't be beaten for smoothness. By 1990, Jaguar had switched from fuel injection by The Prince of Darkness to a system made by Magneti Marelli.
This one is quite rough, and it shows signs of having been parked outdoors with the top down for a few years. Since you can buy nice examples for well under ten grand, restoring this one would have been a money-losing proposition.
Some of you may remember a cameo by a similar XJ-S convertible in the film The Big Lebowski. In it, Bunny Lebowski reveals that none of her toes have been cut off by kidnappers; some suspension of disbelief is required here, because Americans couldn't buy the '90 XJ-S with a manual transmission. Maybe it's a gray-market six-cylinder car.
The price tag on a new 1990 XJ-S convertible was a stunning $57,000, which comes to about $113,000 in inflation-adjusted 2018 dollars. Still, BMW shoppers had to pay $70,000 for a new 750iL that year, and that V12-powered machine didn't even have a convertible top.
Here is V12 power wrapped in soft leather.