More than a touch of the rose-tinted glasses here methinks, an alternative view of the engine is: "Austin Rover withdrew from the rallying scene at the end of the season, but in 1987 all the parts and engines were sold to Tom Walkinshaw Racing, whereupon the V6 engine reappeared under the bonnet of the Jaguar XJ220, this time with turbochargers added."
Well, a little bit: after all, they are local to me and I am always going to be biased as it's a car I love!
I don't think the history of the engine particularly matters. At the end of the day the original concept showcased it as having a big, heavy V12 that was struggling to meet emissions regs. The 6R4 engine was race-bred, lighter and more efficient and not dissimilar to the current Group C car. It was superior in every way to the V12 originally proposed apart from nostalgia. People just have a thing - and seemed to particularly at the end of the '80s - about the number of cylinders in a car. What's more applicable is the right engine for the job.
If you did that today you would be applauded for 'adding lightness', being more like a racing car and increasing drivetrain efficiency. 4WD was the in-thing in the late '80s but supercars with it are derided for not being pure nowadays. It's automotive fashion and that's what gets my goat a bit. The engine and drivetrain change was for design reasons, not cost.
These days nobody remembers the 'little things' like the fact it had the best crash protection in the world and featured proper ground-effect aero, thus being the precursor to every modern supercar...
It also clocked a 7.46 lap of the Nurburgring (before it was cool) which is astonishing given the brake and tyre technology at the time.
Sounds like your TWR is better than the other TWR!
Well, in a way, yeah. I mean, the XJ220 was TWR building to Jaguar design. The XJR-15 was all TWR who wanted to make a road-going race car as opposed to a road car. It has legendary handling issues though and is really a very different kind of car and closer in spirit to their previous Group C efforts, hence the XJR nomenclature.
I don't think Jag ever threatened customers with legal action (though I may be wrong), I think it was the other way round. Recession hit, speculators (who were probably the same people who made a few quid on the F40...) thought they were going to lose out, but they'd signed a contract and Jag gave them the option to buy out of it. They didn't like that but the court sided with Jaguar. I don't know the ins and the outs of it but if the same happened in the current market I'm not sure there would be much sympathy for those that have signed contracts. Again, times change.
As for use of parts from other cars, this is standard for pretty much any supercar. If this made it rubbish nobody would have bought an Enzo! Even the McLaren F1 uses ancillary bits from other cars, IIRC. And it was capable of the top speed, the 217mph was done on a bowl which equates to a larger straight-line speed of 223mph.
With modern engine management and a little bit of fettling from Don Laws I believe they put out in the region of 700bhp, and you can buy Group C style brake upgrades to match.
No car is perfect and the XJ220 has its flaws - then again so does the F40 and I love that too. I just think there are a lot of anecdotes that aren't wholly true and I think time will eventually be kind to it. Compared to its contemporaries it is/was impressive and quicker than all of them until the F1, replete with unlimited resources, came on to the scene.
