I own a near mint 2003 ( X308) XJR ( 39000 miles) . A good friend of mine has an absolutely beautiful near mint 4.0 L Normally aspirated VDP.
We did a bit of comparisons between the two cars (each driving each others). Our findings were that the VDP is the top of the line 'cruising saloon" with a "softer suspension and plenty of power for the weight of such a gorgeous British luxury sedan.. The rear seat "picnic tables and the much larger leg room in the rear seating is my favorite...sweet...
The XJR is a totally different animal if you would. My friend described it as a British luxury "muscle car" that while not quite as "elegant" as the VDP and with a stiffer ride, is an absolute "horror show" shockingly fast beastie. The snarling " big cat" face on the front of the grille makes more than a truthful statement as to what the XJR is all about...."horror show !" Un Godly fast for a car of this weight with a relatively small block V8..Blisteringly fast is a better description.
Bottom line? If you're chauffeuring your son/daughter to their wedding take the sumptuous VDP .. Glorious ! . Rivaled only by a Rolls or a Bently IMO...oozing "class"
If you want to horrify the BMW/ Lexus / Merc/ Mustang muscle car crowd unleash the "whine" of the XJR supercharger. The look on their faces when they hear a Jag that sounds more like an FA 18 Hornet jet
than an than a 5000lb British luxury car is always good for some laughs. I call it the "what the hell was that ?" look.
The 4.o litter Jag V8 is a sweet motor. Put the Eaton supercharger on it and it moves it to a whole different world. Test drive the two versions of this great motor and you tell us what you think

 

And then there is the Super V8 which combines the two sets of attributes.

 

The XJR belongs to a class that did not exist back, when Jaguar was all about "refinement and elegance", i.e. the "over-10-seconds-zero-to-sixty-who-cares" days. The athletic XJR belongs to a group that was originally suggested by the German industry (BMW "M" cars and Merc "AMG" cars), where rather large sedans were bestowed upon with performance previously reserved only for serious sports cars.

Today, this concept has reached incredible levels where, who else but the Germans, again, have a new large sedan doing now 3.3 seconds 0 to 60 (2012 and 2014 Panamera Turbo), leaving our otherwise impressive XJR almost two entire seconds behind (XJR is 5.2 sec.).

Heck, even the rather heavy "luxury standard" Bentley and Rolls aren't limited to "comfort and elegance" anymore with power plants that move these heavy objects into the lower 4 seconds 0 to 60.

The fact is that you get conditioned to power and you wouldn't go back once you've lived with that power. Not that I wouldn't enjoy a slower car, such as an XJS?

Cheers,

 

Yes, the super v8 is the answer if you like the smooth ride, and have the space in the garage. Sadly the superV8 is about 6" too long for my garage, so instead I bought both the XJR and XJ8.

 

The Super V8 is no less than the dream car.
Wouldn't mind a BRG, Magnolia, with some 14,500 miles on it? Yes!

Cheers,

 

If you don't mind an added 100K miles I know where to find that car

 

The X308 is a car to own within the first 100K miles. Owning beyond that is at one's own peril. Mine is already at 91,000 and I know that several issues will have to be addressed sooner or later. I will try to cope with it because I already own it, but I would stay away from buying one with over 100K.

Cheers,