Despite of the new name "XJ8", it is not a new car. The original XJ6 launched in the 70's, since then there was 2 major revisions - the first one (1986) introduced a more boxy body with square lamps, plus an all new 24valves straight 6 ; the second one is in 1993, it was polished with better build quality, vastly improved reliability, smoothened engine and switches back to the 4 circular lamps configuration. This was not a major improvement, but it cures the weakest points troubling XJ6 for a long time - quality and reliability.  

However, XJ6 still being inferior to its competitors in terms of the no. of cylinder - all of them has 8. Although the AJ6 is smooth and extremely responsive, it reached its due date and hardly increase power and refinement further. Logically, XK8 coupe's V8 should be the most obvious replacement.  

In fact, without planning to use this V8 in the larger-volume production sedan, who would develop it solely for the coupe ? This dohc 32 valves all-alloy AJ-V8 (available in 240hp 3.2 and 290hp 4.0 with variable valve timing) will not only replace the AJ6 engine, but also the long-serving V12. It brings highest-ever level of power, smoothness and eagerness to the XJ series sedan. Further accompany with XK8's 5 speed automatic, XJ8 is vastly improved.  

Besides, retuned suspensions and a modernised interior are also new features.  

With the marvellous engine and crisp handling, XJ8 reminds us that the company used to build sporty sedans and sports cars since WWII. Until you have driven a BMW, you will find XJ8 being the most sporty luxurious sedan. Besides, surprisingly, it rides even more supple than Lexus LS400, especially on rough road. While the German cars are tuned for the flat autobahn, XJ8 remains to be the best ride luxurious sedan available.  

Its fatal weakness is the interior space. Since the original, XJ6/8 used to be the crampest luxurious sedan. Curiously, Jaguar has no intention to enlarge the cabin space, some said because the re-construction is too costly for Jaguar, some said because Jaguar prefer to maintain the current sleek styling. Anyway, it is too short of headroom and rear seat leg room, even compare with smaller cars such as BMW 5 series / Mercedes E class. Imagine, what will it be if it offers a descent cabin room ? 5 stars, I have no hesitation. 
 

Jaguar XJR

Like the previous XJR, the new V8 version employs an US-built Eaton supercharger. In order to make good use of the free-revving characteristic of the V8, the new supercharger is considerably larger thus provide the necessary air-flow in high rpm. As a result, peak power rise for 48hp and now appears as high as 6150rpm, even 50rpm higher than the normally-aspirated version ! 

To cope with the increased power, ZF provides the 5A gearbox which Mercedes S600 also employing.  

Wider and lower profile tyres add a lot of grip. Its handling is secure, balance and relaxing, not as involving as BMW M5 but far better than other competitors like Audi A8 and Alpina B10 (modified from BMW540i). You drive XJR with ease but still out-perform other sport sedans - 0-60mph in merely 5.3sec ! More important, it is also benefited from the standard car's supple ride, make it the most comfortable sports sedan. That's why XJR is so pleasing.