Sorry chaps but me and the C5 have parted company and I am now using a rather nice 56 plate Toyota Prius T4 as my daily drive. I realised that £700 for tax and insurance is a no no and I needed something easier on the wallet. The Prius was bought locally and has just turned 60k so low miles and one owner. After one week driving it is averaging 58mpg against 28mpg (on a good day) for the C5 and £10/year road tax. Insurance appears to be similar to the C5 but I will shop round next year as the owners club also have an insurance scheme.
It's lovely to drive now I've sussed the start up procedure and is very quiet on the road, the main noise being tyres. I wouldn't describe it as a fast car although 0-60 is advertised as 11 seconds. I find it proceeds at a stately pace!

I haven't mastered the art of rapid acceleration yet and joining the motorway from a slip road is slightly worrying to say the least but once upto speed it will cruise at 60 all day long. I found the easiest way to pick up speed is to progressively press the pedal down, stamp on the pedal and there is mucho noise but not mucho go, it's weird like a crazily slipping clutch but reading the technical stuff it doesn't have a gearbox as such just some sort of set up between two electric motors (I think!). It's very comfy to sit in and drive although at first I found the large central box/armrest thing between the seats was very obtrusive but I haven't really noticed it for the last day or two. Steering is very direct, like the original Mini and it has a very tight turning circle.
The heating controls are something else being multi multi multi adjustable, but the annoying thing for me is it's all touchscreen. I nearly ran up the kerb last night messing about. I'm also not sure if the heating comes just from the engine or electrically as some people appear to suggest but it takes a while to warm up in this cold weather. Once warm though it does a good job of controlling the temperature.
I do still have the BX and I'm looking forward to getting the cambelt done as soon as the weather warms up so I can get out and about.