What are the running costs like on A Bentley GT?

[lambo_xx]

I was hoping someone could answer a couple questions for me:
How often do they need serviced?
How much do the cost to service from main dealers?
What’s the reliability like?
I realise this sounds like a fairly stupid question, but how fast are they compared to say a DB9? Looking at the figures they seem to be about the same, but I seem to remember Top Gear doing a drag race with them and the Bentley lost buy quite a bit.
What are the rear seats like? The ones in the DB9 are just shocking, but the back seats in my old 911 weren’t too bad.
I’m speaking about earlier cars specifically, not sure if that makes much of a difference.

Thanks for the help in advance.