Excel as everyday car?

[tvrheart]

I am looking to change my BMW and have always been after a Lotus Excel, just wondering how feasible it might be as an everyday wagon. I have <£5k budget wise, I do about 350 miles a week, some of that is stop/start M25 stuff. Firstly, roughly what mpg could I expect, around 20, or less/more? How much is maintainance on average? Finally, can anyone give any first hand experience, i.e. Are they reliable, overheat in traffic, general views etc.
Appreciate this is a bit of a how-long-is-a-piece-of-string question but comments will be most welcome!
Thanks in advance,
Chris