I think many folk are missing the point of Renaultsport's Twingo as I don't believe for a second Renault even consider the 500 to be a natural competitor.
The Twingosport in Cup form is little over £10K and has an insurance group of 8. Even a "full fat" model with cup pack added is still only £12K or so, about same price as a 1,4 16V 500 and lets face it, it's not even at the races.
A 500 Abarth is over £14K and is insurance group 13, add SS kit and its upto group 14 and nearly £17K, and that's before adding any extras, before you know it you could be looking at a £20K car, that's expensive in anyone's books, in fact 2X Twingosports. It is therefore considerably more expensive to not only purchase, but to insure. And that is paramount to any young driver, £4k in your pocket and maybe add another £500 for insurance makes it a totally different proposition. 2mpg is nothing that anyone who actually cares about driving a fun car, and is never ever going to be a selling point over driver involvement and feedback.
A Clio 200 Cup is about £15K and group 15 and is considerably faster, bigger, better handling drivers car.
THe 500Abarth is really pitched against MINI Copper (not S that's in different league) more a feelgood fashoin car that many folk detest with a pashion over what they consider contrived loosk and dodgy interior packaging, these are not my thought sbut ones expressed by many in Pistonheads forum, and dynamically it's no match as many know that under teh skin the MINI is one of the best hatch's ever made.
The whole point of the Twingosport is to give an affordable cheap to run entry level model to younger drivers who then get loyal to the brand and move upto Clio's and Meganes.
The 500Abarth is pretty much a stand alone halo model for the 500, as it may be a step up dynamically going to a GP Abarth but its priced the same unless going very expensive SS kit so not really a big step up in terms of building brand loyalty.
So until Fiat maybe produces a Panda Abarth entry model, and then maybe a Bravo Abarth step up model its not really a full enough range to entice people to move over from other brands as yet.