Re: Nice try
" If the original 500 had an engine of only 479 cc what does that say about the 1.4 or 1.7 litre engines of the new car?"
The FIAT 500 and 500C models are available with an 875cc two-cylinder engine (but producing 85 or 105 bhp, because time has moved on since 1957), and it suits the car very well.
To my mind, FIAT's revival of the 500 is the best relaunch of a historic model by a manufacturer (and to be clear I'm talking about the 2007 model, not the X or L, which are different members of a family of models). BMW's MINI was always much bigger than BMC's original Mini: the original car was what we'd now call a City Car (A segment), but the relaunched model was a "supermini" (B Segment). The new one takes this enlargement even further to almost be a "Small hatchback" (C Segment). And I'd rather not think about the Countryman or Paceman.
"The new cars are not in the same class as the originals"
FIAT has at least kept their 500 in the same size category as its original: a city car. The fact that it's bigger than the 1957 car is more to do with 50 years of crash protection regulations and raised customer expectations regarding cabin noise and comfort, than any desire to bloat the model.
(Incidentally, the 2001 BMW MINI and the 2007 FIAT 500 share the same designer: Frank Stephenson, who now heads design at McLaren. Stephenson left BMW long before the MINI facelift that ended up looking like a Chinese car maker's knock-off of the first one)
As someone who proudly owns an original Mini, I'm sure you understand the idea of owning a car because it has character, even if it might be more expensive and less practical than the alternatives.
If you want the "car as a cheap utility" side of the old 500, FIAT will sell you its descendent: the Panda, a superbly useful and reliable car at an affordable price. The 2007 500 isn't that, and can't be that, because what customers want from a "utilitarian car" are so much higher now: hence the Panda's boxy space-maximising shape. The new 500 model was about recapturing the emotional bond that people had with the old 500 - and with the aforementioned twin-cylinder engine, it's got a lot of that same fun to it.
The 500 L and this X are not relaunches of any old model (although you might make a case for the 500L being a spiritual successor to the 600 Multipla, but it looks completely different). These two new cars are more closely related to each other than to the 500, both mechanically and in terms of size. "500" is now a sub-brand covering what you might call the "want" cars (heat over head); the FIAT brand will deal with the "need" cars (head over heart) like Panda, Punto, etc.