Am I missing something? The S2000 is about the same as a Zed (there or there abouts) isn't it? Group 19/20 insurance, Honda parts prices (Nissanish?), Service interval pretty similar, MPG pretty similar, needs to be thrashed for it to move?
I've used an RX8 (same horrible thrashy torqueless style) for motorway cruising mate......soul destroying lack of torque.
If you want thrills and economy your seriously restricted - dare I say it.....Audi TT.
s2000 doesn't feel as gutless as the RX8, higher insurance than the zed, but i could get 35 mpg out of the s2k on a long drive. and being able to take the roof down just adds to the fun factor, which is why it is so much better than the rx8. as for parts i never had to buy any as it never broke, unlike my zed, which always seemed to have niggles.
If its not gutless and it can turn that kind of MPG back then it might be a good shout.
I had a thread about a getting a Cockster a few weeks back.........lot of bang for your buck and that was mid 30's on a combined cycle