Ah, some very interesting ideas, thanks
I have not driven a Smart Roadster yet Tim, I have driven a couple Fortwos and found the gearbox lazy, though apparently you get used to it. The Clio 182 (not sure if I would willingly opt for the noisier, stiffer and less well equipped Cup) is an appealing car, very cheap to buy and good performance and handling. They are also everywhere so finding a decent one wouldn't be too difficult. Unlike a Smart Roadster which are pretty rare.
I have driven a 2002 Seat Ibiza 1.9TDi 130 Sport, I thought there was something wrong with it as the suspension was the worst I have experienced in any car. I couldn't live with it and so didn't buy that one back then. Id rather have a Skoda Fabia VRS, better looking in my opinion, 5 door and again quite easy to find.
Im not sure on the Mazda 323, I guess it was a looker in its time but I much prefer the slightly later and more rounded version. From what I have seen, they all rust, a lot. Original MX-5 would be ok, I'm not too enthusiastic about them though.
The C4 is ok Franklin, its perhaps not as different as I was hoping for and the VTS doesn't do what I'm looking for, it would be much more expensive than my C5 is to run. Actually the C5 is very cheap to run, road tax is £165 (im ideally looking for something a bit cheaper but quite happy with that), it does 50mpg and insurance is reasonable. Its not a whole lot of fun though
The same engine my C5 has but in a C4 would be ok.
I do like GSs but can't see one working as my every day car.
Rust is a big pet hate of mine and they do like to fiz away a little, I can't see it lasting through many winters!
I think your right Dommo, I have bought C5s as they do everything I need in a car, however the Xantia and especially XM will do that and so it makes sense to have something a bit more different to use every day, I dont need 3 big cars. The Xm could be my choice for long distances and when i need space. The Honda Insight is certainly an interesting and different car, I really like those. None on autotrader, that would make one a little hard to find. The ebay one has done 160K, impressive! I gather the batteries need changing at some point, im sure it being stood for a year would not have done them any favours.
I suppose I kind of want the almost impossible, something which is fun to drive, is a little different but also cheap to keep, run and fuel.
So with that in mind, the list I have so far is:
Audi A2 - Have always liked these, its not in the slightest sporty but it is a bit different. If had with a 1.4TDi engine they will be very efficient. Virtually no depreciation as they are getting more desirable.
Citroen C2 - perhas a GT or VTS, or even a HDi. Cheap to buy and great fun in sporty trim.
Citroen C1 - the sensible choice as far as running costs and reliability go. Few modern cars are cheaper to buy and run, however I do find them good fun too. Cheap to buy, slow depreciation and very simple = less to go wrong.
Fiat Panda 100HP - They look great in my opinion, have a great stance, well equipped and almost practical. Drove one yesterday and it was a lot more fun than I was expecting. Really do want one of these at the moment, probably drop like a stone in value, not be great on fuel, but it will be fun and its an entertaining drive.
Mini Cooper - not sure about this, too many bought for a fashion item rather than a decent little drivers car. Have a pretty poor reliability rep too. Drives well, plenty to choose from, about the size im looking for.
Renault Clio 182 - good fun, easy to get hold of, look good and have a lot of performance and great handling. I do find the driving position a bit cramped and awkward in Clios.
Skoda Fabia VRS - diesel with lots of torque, 5 doors and looks good
Smart Roadster - possibly the most fun out of all of my thoughts, however will I get fed up with it quickly?
It has to be cheap to keep otherwise having 3 cars for any period is not going to work for me and something else will have to go.
Tim, my C5 is a diesel yes, a 2.0HDi 138bhp with 35,000 miles.
.... There are some very uneducated people around here 
That one does look nice...