The Arnage was based on a low-volume platform engineered on a very tight budget and the Continental coupé was, arguably, even more outdated in terms of its underpinnings.
When VW started work on its first brand-new Bentley, it employed the platform of the big Phaeton saloon. For the Continental GT, this structure was greatly modified, and it provided a super-modern and rigid basis for the new-age Bentley.
The downside was that it used the period Audi powertrain: a longitudinally mounted engine sited ahead of the front axle. So the whole weight of the engine was, in effect, hanging out ahead of the front wheels.
This is highly undesirable when tuning a car for ultimate handling, although the use of permanent all-wheel drive on the Continental GT did offset the problem to an extent.