The Silver Seraph was the first Rolls Royce in the modern era to have a V12 engine, which was developed by BMW, Rolls Royce's parent company. This engine was paired with a 5 speed automatic transmission.
Among the cool features on the Silver Seraph were the digital engine management and adaptive ride control, which adjusted on all four wheels to keep the ride smooth and level.
The Silver Seraph chassis was just about identical to the Bentley Arnage. They were quite different on the inside, so luxury car buyers did have a choice between cars with different offerings. They look very similar on the exterior.
The major difference between the Silver Seraph and the Arnage was the engine. The Rolls Royce was slow but offered a comfortable ride, while the Bentley twin turbo V8 was more of a performance car that was fun to drive.
The Silver Seraph was discontinued many years ago, but you can still find them for sale in slightly used condition in a few places. The first place I'd look might surprise some people. I go to eBay. There are usually several Rolls Royces listed on there at any given time.