I'm amused that 5th Gear commented that the 500 has more room in the rear of the car. Not true. I (at 6' 2") can easily fit in any Mini. I do not fit at all in the 500, not even close, there is no rear headroom, I'd estimate anyone over 5'8" won't fit in the back.
Different class of car at the end of the day, not really in competition.
When the Arbarth comes out, I'm betting they'll pitch-it against the current Cooper, in which case the 500 will win again. Guess they won't want to lose all of that lovely advertising money from the Fiat group.
*** What would be interesting to see would be the lap times for the old MINI One, Cooper, Cooper S and JCW on similar spec tyres, etc.