I've been rolling this around in my head for some months no and I stumbled across this...
http://charlotte.craigslist.org/cto/1661649565.html
a 1.2l and a decent shape (albeit a touch blocky) this would make a good car to hit an easy 50mpg and a possible 60+. I have owned one before but with the 1.5l and saw 35-40 all day long.
if I were to get tis I would pull the head and have it shaved a bit and add singh groves. I would then swap the carburetor for EFI so I can more easily control the mixture. swap the 4 speed for a 5 speed (although 5th is virtually useless in these) lower it a bit and smooth the wheels.